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1991 | show all back to the top of all publications back to the year overview R. Qelibari, E. Cruz Ortiz, N. van Treel, F. Lombeck, C. Schare, A. Münchinger, N. Dumbadze, G. Titvinidze, C. Klose, S. Vierrath74 µm PEEK-Reinforced Sulfonated Poly(phenylene sulfone)-Membrane for Stable Water Electrolysis with Lower Gas Crossover and Lower Resistance than Nafion N115 2024 Adv. Energy Mater. , page : 2303271 M.U. Iturritza, P. Mlotshwa, J. Gantelius, T. Alfvén, E. Loh, J. Karlsson, C. Hadjineophytou, K. Langer, K. Mitsakakis, A. Russom, H.N. Jönsson, G. GaudenziAn Automated Versatile Diagnostic Workflow for Infectious Disease Detection in Low-Resource Settings 2024 Micromachines , volume : 15, issue : 6, page : 708 V. Zieger, E. Woehr, S. Zimmermann, D. Frejek, P. Koltay, R. Zengerle, S. KartmannAutomated Nanodroplet Dispensing for Large-Scale Spheroid Generation via Hanging Drop and Parallelized Lossless Spheroid Harvesting 2024 Micromachines , volume : 15, page : 231 D. Straubinger, P. Koltay, R. Zengerle, S. Kartmann, Z. ShuBulge-Free and Homogeneous Metal Line Jet Printing with
StarJet Technology 2024 Micromachines , volume : 15, page : 743 R. Kronstein-Wiedemann, J. Thiel, D. Sürün, M. Teichert, S. R. Künzel, S. Zimmermann, L. Wagenführ, F. Buchholz, T. TonnCharacterization of immortalized bone marrow erythroid progenitor adult (imBMEP-A)—The first inducible immortalized red blood cell progenitor cell line derived from bone marrow CD71-positive cells 2024 Cytotherapy , volume : 26, issue : 11, pages : 1362 - 1373 K. Seteiz, J. N. Häberlein, P. A. Heizmann, L. Bohn, S. Vierrath, J. DischEffect of Ionomer Content and Ag/C Catalyst Surface Area on the Performance of CO2 Electrolysis to CO 2024 ACS Appl. Eng. Mater , volume : 2, issue : 6, page : 1654 A. Klebes, H. Ceren Ates, Rene D. Verboket, G. A. Urban, F. von Stetten, C. Dincer, S. M. FrühEmerging multianalyte biosensors for the simultaneous detection of protein and nucleic acid biomarkers 2024 Biosensors and Bioelectronics , volume : 244, page : 115800 L. Niebling, R. Nitzsch, T. Sieksmeyer, V. Haskamp, J. Kissenkötter, A. Abd El Wahed, T. Teufel, H. Hermann, N. Paust, A. R. HomannFast and on-site animal species identification in
processed meat via centrifugal microfluidics and
isothermal amplification 2024 LabChip , volume : 24, page : 975 H. Liepold, H. Nguyen, P. A. Heizmann, C. Klose, S. Vierrath, A. MünchingerGas Transport Resistance of Hydrocarbon-Based Catalyst Layers in Proton-Exchange Membrane Fuel Cells 2024 Journal of The Electrochemical Society , volume : 171, page : 054509 H. Liepold, A. Bird, P. A. Heizmann, H. Fadlullah, H. Nguyen, C. Klose, S. Holdcroft, A. Kusoglu, S. Vierrath, A. MünchingerHigh protonic resistance of hydrocarbon-based cathodes in PEM fuel cells under low humidity conditions: Origin, implication, and mitigation 2024 Journal of Power Sources , volume : 624, page : 235537 M. Klingenhof, H. Trzesniowski, S. Koch, J. Zhu, Z. Zeng, L. Metzler, A. Klinger, M. Elshamy, F. Lehmann, P. W. Buchheister, A. Weisser, G. Schmid, S. Vierrath, F. Dionigi, P. StrasserHigh-performance anion-exchange membrane water electrolysers using NiX (X = Fe,Co,Mn) catalyst-coated membranes with redox-active Ni–O ligands 2024 Nature Catalysis O. Rajabnia, A. Ernst, N. Lass, L. Riegger, R. ZengerleHighly Parallel Droplet Dispensing Approach to Provide Homogeneous and Controllable Droplet Arrays for Diagnostic Test Manufacturing 2024 micromachines , volume : 15, page : 824 Z. Khan, D. Gururajan, P. Koltay, S. Kartmann, R. Zengerle, Z. ShuHybrid 3D Printing of Molten Metal Microdroplets and Polymers for Prototyping of Printed Circuit Boards Featuring Interdigitated 3D Capacitors 2024 EEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, IEEJ Trans 2024 Z. Khan, A. Saphala, S. Kartmann, P. Koltay, R. Zengerle, O. Amft, Z. ShuHybrid Printing of Conductive Traces from Bulk Metal for Digital Signals in Intelligent Device 2024 Micromachines , volume : 15, page : 750 J. Stiegeler, T. Mittermeier, L. Tsikonis, T. Lehre, S. VierrathInfluence Factors of Platinum Dissolution in Proton Exchange Membrane Fuel Cells: A Sensitivity Study 2024 J. Electrochem. Soc , volume : 171, page : 054517 B. Johannsen, D. Baumgartner, M. Karpíšek, D. Stejskal, N. Paust, R. Zengerle, K. MitsakakisIntegration of a bead-based immunoassay on a commercial PCR-performing POC device 2024 Proceedings , volume : 97, page : 166 Z. Khan, D. Gururajan, S. Kartmann, P. Koltay, R. Zengerle, Z. ShuIterative printing of bulk metal and polymer for additive manufacturing of multi-layer electronic circuits 2024 npj Adv. Manuf. , volume : 1, issue : 1 R. Weber, M. Klingenhof, S. Koch, L. Metzler, T. Merzdorf, J. Meier-Haack, P. Strasser, S. Vierrath, M. SommerMeta-kinks are key to binder performance of poly(arylene piperidinium) ionomers for alkaline membrane water electrolysis using non-noble metal catalysts 2024 J. Mater. Chem. A , volume : 12, page : 7826 F. Pescher, J. Stiegeler, P. A. Heizmann, C. Klose, S. Vierrath, M. BreitwieserPt/C catalysts synthesized in a commercial particle atomic layer deposition system enabling improved durability in fuel cells 2024 RSC Advances , volume : 44 L. Bohn, J. Kieninger, S. J. Rupitsch, C. Klose, S. Vierrath, J. DischReference Electrode Types for Zero-Gap CO2 Electrolyzers: Benefits and Limitations 2024 Advanced Science , volume : 11, page : 32 V. Zieger, D. Frejek, S. Zimmermann, G. A. A. Miotto, P. Koltay, R. Zengerle, S. KartmannTowards Automation in 3D Cell Culture: Selective and Gentle High-Throughput Handling of Spheroids and Organoids via Novel Pick-Flow-Drop Principle 2024 Adv Healthc Mater , page : e2303350 J. Schlanderer, H. Hoffmann, J. Lüddecke, A. Golubov, W. Grasse, E. V. Kindler, T. A. Kohl, M. Merker, C. Metzger, V. Mohr, S. Niemann, C. Pilloni, S. Plesnik, B. Raya, B. Shresta, C. Utpatel, R. Zengerle, M. Beutlerd, N. PaustTwo-stage tuberculosis diagnostics: combining
centrifugal microfluidics to detect TB infection
and Inh and Rif resistance at the point of care with
subsequent antibiotic resistance profiling by
targeted NGS 2024 LabChip , volume : 24, page : 74 back to the year overview K. Yildirim, H. Fadlullah, C. Schwarz, F. Lombeck, C. Klose, S. Vierrath, M. Breitwieser30μm Thin Anode Gas Diffusion Layers for OptimizedPEM Fuel Cell Operation at 120 °C and Low Relative Humidity 2023 Adv. Energy Sustainability Res , page : 2300179 F. Fischer, A. Doll, D. Uereyener, S. Roenneberg, C. Hillig, L. Weber, V. Hackert, P. Seiringer, J. Thomas, P. Anand, L. Graner, F. Schlenker, R. Zengerle, M. Jargosch, F. J. Theis, C. B. Schmidt-Weber, T. Biedermann, M. Howell, K. Reich, M. Menden, N. Garzorz-Stark, F. Lauffer, S. Eyerich394 Gene expression based molecular test proves clinical validity as diagnostic aid for the differential diagnosis of psoriasis and eczema in formalin fixed and paraffin embedded tissue 2023 British Journal of Dermatology , volume : 188, issue : 3 H. Nguyen, J. Stiegeler, H. Liepold, C. Schwarz, S. Vierrath, M. BreitwieserA Comparative Study of Conditioning Methods for Hydrocarbon-Based Proton-Exchange Membrane Fuel Cells for Improved Performance 2023 Energy Technol. , page : 2300202 J. Weygant, F. Koch, K. Adam, K. Tröndle, R. Zengerle, G. Finkenzeller, S. Kartmann, P. Koltay, S. ZimmermannA Drop-on-Demand Bioprinting Approach to Spatial Arrangement of Multiple Cell Types and Monitoring Their Cell–Cell Interactions towards Vascularization Based on Endothelial Cells and Mesenchymal Stem Cells 2023 Cells , volume : 12, issue : 4, page : 646 P. A. Heizmann, H. Nguyen, M. von Holst, A. Fischbach, M. Kostelec, F. J. Gonzalez Lopez, M. Bele, L. Pavko, T. Đukić, M. Šala, F. Ruiz-Zepeda, C. Klose, M. Gatalo, N. Hodnik, S. Vierrath, M. BreitwieserAlternative and facile production pathway towards obtaining high surface area PtCo/C intermetallic catalysts for improved PEM fuel cell performance 2023 RSC Adv , volume : 13, pages : 4601 - 4611 J. Disch, S. Ingenhoven, S. VierrathBipolar Membrane with Porous Anion Exchange Layer for Efficient and Long-Term Stable Electrochemical Reduction of CO2 to CO 2023 Adv. Energy Mater. , page : 2301614 K. Seteiz, J. N. Häberlein, P. A. Heizmann, J. Disch, S. VierrathCarbon black supported Ag nanoparticles in zero-gap CO2 electrolysis to CO enabling high mass activity 2023 RSC Advances , volume : 27 P. Sardana, M. Zolfaghari, G. Miotto, R. Zengerle, T. Brox, P. Koltay, S. KartmannDropletAI: Deep Learning-Based Classification of Fluids with
Different Ohnesorge Numbers during Non-Contact Dispensing 2023 Fluids , volume : 8, page : 183 A. Klebes, H. C. Ates, R. D. Verboket, G. Urban, F. von Stetten, C. Dincer, S. M. FrühEmerging multianalyte biosensors for the simultaneous detection of protein and nucleic acid biomarkers 2023 Biosensors and Bioelectronics , page : 115800 T. T. Bachmann, K. Mitsakakis, J. P. Hays, A. van Belkum, A. Russom, G. Luedke, G. Skov Simonsen, G. Abel, H. Peter, H. Goossens, J. Moran-Gilad, J. Vila, K. Becker, P. Moons, R. Sampath, R. W Peeling, S. Luz, T. van Staa, V. Di Gregori, JPIAMR AMR-RDT Working GroupExpert guidance on target product profile development for AMR diagnostic tests 2023 BMJ Glob Health , volume : 18, issue : 8, page : e012319 F. Fischer, A. Doll, D. Uereyener, S. Roenneberg, C. Hillig, L. Weber, V. Hackert, M. Meinel, A. Farnoud, P. Seiringer, J. Thomas, P. Anand, L. Graner, F. Schlenker, R. Zengerle, P. Jonsson, M. Jargosch, FJ Theis, CB Schmidt-Weber, T. Biedermann, M. Howell, K. Reich, K. Eyerich, M. Menden, N. Garzorz-Stark, F. Lauffer, S. EyerichGene expression based molecular test as diagnostic aid for the differential diagnosis of psoriasis and eczema in formalin fixed and paraffin embedded tissue, microbiopsies and tape strips 2023 The Journal of Investigative Dermatology G. Miotto, K. Thiemann, M. Rombach, R. Zengerle, S. KartmannHolographic PIV/PTV for nano flow rates - a study in the 70 to 200 nL/min range 2023 Biomedical engineering , volume : 68, issue : 1, pages : 97 - 107 Y.-K. Lai, Y.-T. Kao, J. Hess, S. Calabrese, F. von Stetten, N. PaustInterfacing centrifugal microfluidics with linear-oriented 8-tube strips and multichannel pipettes for increased throughput of digital assays 2023 Lab on a Chip , volume : 23, pages : 2623 - 2632 F. Schlenker, P. Juelg, J. Lüddecke, N. Paust, R. Zengerle, T. HutzenlaubNanobead handling on a centrifugal microfluidic LabDisk for automated extraction of cell-free circulating DNA with high recovery rates 2023 Analyst D. Grijalva Garces, S. Strauß, S. Gretzinger, B. Schmieg, T. Jüngst, J. Groll, L. Meinel, I. Schmidt, H. Hartmann, K. Schenke-Layland, N. Brandt, M. Selzer, S. Zimmermann, P. Koltay, A. Southan, G. E. M. Tovar, S. Schmidt, A. Weber, T. Ahlfeld, M. Gelinsky, T. Scheibel, R. Detsch, A. R. Boccaccini, T. Naolou, C. Lee-Thedieck, C. Willems, T. Groth, S. Allgeier, B. Köhler, T. Friedrich, H. Briesen, J. Buchholz, D. Paulus, A. von Gladiss, J. HubbuchOn the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field 2023 Biofabrication , volume : 16, page : 015002 Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. ShuOne-Stop Hybrid Printing of Bulk Metal and Polymer for 3D Electronics 2023 Advanced Engineering Materials , page : 2300922 B. Johannsen, D. Baumgartner, M. Karpíšek, D. Stejskal, N. Boillat-Blanco, J. Knüsli, M. Panning, N. Paust, R. Zengerle, K. MitsakakisPatient Stratification for Antibiotic Prescriptions Based on the Bound-Free Phase Detection Immunoassay of C-Reactive Protein in Serum Samples 2023 Biosensors , volume : 13, page : 1009 S. Calabrese, A. M. Markl, M. Neugebauer, S. J. Krauth, N. Borst, F. von Stetten, M. LehnertReporter emission multiplexing in digital PCRs (REM-dPCRs): direct quantification of multiple target sequences per detection channel by population specific reporters 2023 Analyst , volume : 148, pages : 5243 - 5254 S. Koch, L. Metzler, S. Kilian, P. A. Heizmann, F. Lombeck, M. Breitwieser, S. VierrathToward scalable production: catalyst‐coated membranes (CCMs) for anion‐exchange membrane water electrolysis via direct bar coating 2023 Advanced sustainable systems , volume : 7, page : 2200332 V. Zieger, D. Frejek, S. Zimmermann, G. A. A. Miotto, P. Koltay, R. Zengerle, S. KartmannTowards Label-Free Standardization in 3d Cell Culture: Automated, Selective and Gentle High-Throughput Handling of Spheroids and Organoids via Novel Pick-Flow-Drop Principle 2023 Adv Healthc Mater , page : e2303350 back to the year overview E. Kipf, F. Schlenker, N. Borst, M. Fillies, R. Kirschner-Schwabe, R. Zengerle, C. Eckert, F. von Stetten, M. LehnertAdvanced minimal residual disease monitoring for acute lymphoblastic leukemia with multiplex mediator probe PCR 2022 J. Mol. Diag , volume : 24, issue : 1, pages : 57 - 68 M. Neugebauer, C. E. Grundmann, M. Lehnert, F. von Stetten, S. M. Früh, R. SüssAnalyzing siRNA Concentration, Complexation and Stability in
Cationic Dendriplexes by Stem-Loop Reverse Transcription-qPCR 2022 Pharmaceutics , volume : 2022, issue : 14, page : 1348 Dornhof J, Zieger V, Kieninger J, Frejek D, Zengerle R, Urban GA, Kartmann S, Weltin ABioprinting-based automated deposition of single cancer cell spheroids into oxygen sensor microelectrode wells 2022 LabChip , volume : 8, issue : 22, pages : 4369 - 4381 C. Mills, E. Batista, H. Bissig, F. Ogheard, A. W. Boudaoud, O. Büker, K. Stolt, J. Morgan, S. Kartmann, K. Thiemann, G. Miotto, A. Niemann, S. Klein, G. Ratering, J. LöttersCalibration methods for flow rates down to 5 nL/min and validation methodology 2022 Biomed. Eng.-Biomed. Tech. E. Balogun, P. Mardle, H. Nguyen, M. Breitwieser, S. HoldcroftCatalyst layers for fluorine‐free hydrocarbon PEMFCs 2022 Electrochimica Acta , volume : 401, page : 139479 K. Tröndle, G. Miotto, L. Rizzo, R. Pichler, F. Koch, P. Koltay, R. Zengerle, S. S. Lienkamp, S. Kartmann, S. ZimmermannDeep Learning-Assisted Nephrotoxicity Testing with Bioprinted Renal Spheroids 2022 Int. J. Bioprint , volume : 8, issue : 2, page : 528 V. Burchak, F. Koch, L. Siebler, S. Haase, V. K. Horner, X. Kempter, G. B. Stark, U. Schepers, A. Grimm, S. Zimmermann, P. Koltay, S. Strassburg, G. Finkenzeller, F. Simunovic, F. LampertEvaluation of a Novel Thiol–Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells 2022 Int. J. Mol. Sci. , volume : 23, page : 7939 H. Nguyen, C. Klose, L. Metzler, S. Vierrath, M. BreitwieserFully Hydrocarbon Membrane Electrode Assemblies for Proton Exchange Membrane Fuel Cells and Electrolyzers: An Engineering Perspective 2022 Adv. Energy Mater. , volume : 2022, page : 2103559 J. Disch, L. Bohn, S. Koch, M. Schulz, Y. Han, A. Tengattini, L. Helfen, M. Breitwieser, S. VierrathHigh-resolution neutron imaging of salt precipitation and water transport in zero-gap CO2 electrolysis 2022 nature communications , volume : 13, page : 6099 G. Miotto, K. Thiemann, M. Rombach, R. Zengerle, S. KartmannHolographic PIV/PTV for nano flow rates–A study in the 70 to 200 nL/min range 2022 Biomedical Engineering B. Johannsen, D. Baumgartner, L. Karkossa, N. Paust, M. Karpíšek, N. Bostanci, R. Zengerle, K. MitsakakisImmunoDisk - a fully automated bead-based immunoassay cartridge with all reagents pre-stored 2022 Biosensors , volume : 12, issue : 6, page : 413 H. Nguyen, D. Sultanova, P. A. Heizmann, S. Vierrath, M. BreitwieserImproving the efficiency of fully hydrocarbon-based proton-exchange membrane fuel cells by ionomer content gradients in cathode catalyst layers 2022 Materials Advances , volume : 23 S. Hin, N. Paust, M. Rombach, J. Lüddecke, M. Specht, R. Zengerle, K. MitsakakisMagnetophoresis in Centrifugal Microfluidics at Continuous Rotation for Nucleic Acid Extraction 2022 Micromachines , volume : 13, page : 2112 F. Koch, O. Thaden, S. Conrad, K. Tröndle, G. Finkenzeller, R. Zengerle, S. Kartmann, S. Zimmermann, P. KoltayMechanical properties of polycaprolactone (PCL) scaffolds for hybrid 3D-bioprinting with alginate-gelatin hydrogel 2022 J. Mech. Behav. Biomed. Mat. , volume : 130, page : 105219 L. Bohn, M. von Holst, E. Cruz Ortiz, M. Breitwieser, S. Vierrath, C. KloseMethods— A Simple Method to Measure In-Plane Electrical Resistance of PEM Fuel Cell and Electrolyzer Catalyst Layers 2022 J.Electrochem. Soc. , volume : 169, issue : 5, page : 054518 Y.-T. Kao, S. Calabrese, N. Borst, M. Lehnert, Y.-K. Lai, F. Schlenker, P. Juelg, R. Zengerle, P. Garstecki, F. von StettenMicrofluidic One-Pot Digital Droplet FISH Using LNA/DNA Molecular Beacons for Bacteria Detection and Absolute Quantification 2022 Biosensors , volume : 12, issue : 4, page : 237 A. Klebes, A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. FrühMultianalyte lateral flow immunoassay for simultaneous detection of protein-based inflammation biomarkers and pathogen DNA 2022 Sensors and Actuators B: Chemical , volume : 355, page : 131283 S. Hennig, Z. Shu, L. Gutzweiler, P. Koltay, F. von Stetten, R. Zengerle, S. M. FrühPaper-based open microfluidic platform for protein electrophoresis and immunoprobing 2022 Electrophoresis , volume : 43, issue : 4, pages : 621 - 631 B. Afacan, V. Özgen Öztürk, G. Emingil, T. Köse, K. Mitsakakis, N. BostanciSalivary secretory leukocyte protease inhibitor levels in patients with stage 3 grade C periodontitis: a comparative cross-sectional study 2022 Scientific Reports , volume : 12, issue : 1, page : 21267 S. Koch, L. Metzler, S. K. Kilian, P. A. Heizmann, F. Lombeck, M. Breitwieser, S. VierrathToward Scalable Production: Catalyst-Coated Membranes (CCMs) for Anion-Exchange Membrane Water Electrolysis via Direct Bar Coating 2022 Adv. Sustainable Syst. , page : 2200332 S. Koch, J. Disch, S. K. Kilian, Y. Han, L. Metzler, A. Tengattini, L. Helfen, M. Schulz, M. Breitwieser, S. VierrathWater management in anion-exchange membrane water electrolyzers under dry cathode operation 2022 RSC Adv , volume : 12, pages : 20778 - 20784 back to the year overview A. Homann, L. Niebling, S. Zehnle, M. Beutler, L. Delamotte, M.C. Rothmund, D. Czurratis, K.-D. Beller, R. Zengerle, H. Hoffmann, N. PaustA microfluidic cartridge for fast and accurate diagnosis of Mycobacterium tuberculosis infections on standard laboratory equipment 2021 Lab on a Chip , volume : 21, issue : 8, pages : 1540 - 1548» show abstract « hide abstract Abstract We present a novel centrifugal microfluidic approach for fast and accurate tuberculosis (TB) diagnosis based on the use of standard laboratory equipment. The herein presented workflow can directly be integrated into laboratories with standard equipment and automates complex sample preparation. The system consists of a microfluidic cartridge, a laboratory centrifuge and a standard PCR cycler. The cartridge includes all required reagents and automates collection of bacteria on filter membranes, bacterial lysis, nucleic acid extraction and aliquoting of the DNA extract for PCR analysis. We show that storage of the reagents in aluminium-coated pouches is stable during accelerated storage and transport tests. When the limit of detection was assessed, we found that the cartridge-automated workflow consistently detected 10 CFU ml−1 of mycobacteria in spiked sputum samples. First tests with clinical samples showed a 100% specificity for non-TB specimens. In addition, Mycobacterium tuberculosis (MTB) was re-found in pre-characterized smear microscopy and culture positive sputum samples suggesting a high diagnostic sensitvity. In summary, the novel cartridge-automated workflow enables a flexible and sensitive TB diagnosis without the need to invest in specialized instrumentation. J.F.Hess, M.E.Hess, R.Zengerle, N.Paust, M.Boerries, T.HutzenlaubAutomated library preparation for whole genome sequencing by centrifugal microfluidic 2021 Analytica Chimica Acta , page : 338954 J.-N. Klatt, T.J. Dinh, O. Schilling, R. Zengerle, F. Schmidt, T. Hutzenlaub, N. PaustAutomation of peptide desalting for proteomic liquid chromatography–tandem mass spectrometry by centrifugal microfluidics 2021 Lab on a Chip , volume : 21, issue : 21, page : 2255» show abstract « hide abstract Abstract For large-scale analysis of complex protein mixtures, liquid chromatography – tandem mass spectrometry (LC-MS/MS) has been proven to be one of the most versatile tools due to its high sensitivity and ability to both identify and quantify thousands of proteins in a single measurement. Sample preparation typically comprises site-specific cleavage of proteins into peptides, followed by desalting and concomitant peptide enrichment, which is commonly performed by solid phase extraction. Desalting workflows may include multiple liquid handling steps and are thus error prone and labour intensive. To improve the reproducibility of sample preparation for low amounts of protein, we present a centrifugal microfluidic disk that automates all liquid handling steps required for peptide desalting by solid phase extraction (DesaltingDisk). Microfluidic implementation was enabled by a novel centrifugal microfluidic dosing on demand structure that enabled mapping multiple washing steps onto a microfluidic disk. Evaluation of the microfluidic disk was performed by LC-MS/MS analysis of tryptic HEK-293 eukaryotic cell peptide mixtures desalted either using the microfluidic disk or a manual workflow. A comparable number of peptides were identified in the disk and manual set with 19 775 and 20 212 identifications, respectively. For a core set of 10 444 peptides that could be quantified in all injections, intensity coefficients of variation were calculated based on label-free quantitation intensities. The disk set featured smaller variability with a median CV of 9.3% compared to the median CV of 12.6% for the manual approach. Intensity CVs on protein level were lowered from 5.8% to 4.2% when using the LabDisk. Interday reproducibility for both workflows was assessed by LC-SRM/MS analysis of samples that were spiked with 11 synthetic peptides of varying hydrophobicity. Except for the most hydrophilic and hydrophobic peptides, the average CV was lowered to 3.6% for the samples processed with the disk compared to 7.2% for the manual workflow. The presented centrifugal microfluidic DesaltingDisk demonstrates the potential to improve reproducibility in the sample preparation workflow for proteomic mass spectrometry, especially for application with limited amount of sample material. J.-N. Klatt, T. Hutzenlaub, T. Subkowski, T. Müller, S. Hennig, R. Zengerle, N. PaustBlocking Protein Adsorption in Microfluidic Chips by a Hydrophobin Coating 2021 ACS Appl. Polym. Mater. , volume : 3, issue : 7, pages : 3278 - 3286» show abstract « hide abstract Abstract Microfluidics allows the miniaturization of biochemical analyses. Small dimensions reduce sample and reagent consumption and enhance reaction rates. A downside is that high surface-to-volume ratios increase the unspecific binding of proteins to the substrate material. The resulting sample loss and reagent depletion decrease the sensitivity and specificity of protein-based assays, especially if low concentrations are analyzed. Here, we introduce the hydrophobin coating of microfluidic chips made of cyclic olefin copolymers (COC). The recombinant hydrophobin H*Protein B self-assembles into stable monolayers on hydrophobic surfaces, making them hydrophilic and thus reducing hydrophobic interactions between the chip surfaces and proteins. The substrate and sealing layers of the microfluidic chip were simply dip-coated and subsequently assembled by thermodiffusion bonding, which renders our coating procedure compatible with mass fabrication. Contact angle measurements and atomic force microscopy were used to evaluate the effect of high temperatures (107 °C) on COC substrates coated with H*Protein B. The efficiency of the protein-repellent coating was evaluated by depletion experiments with bovine serum albumin, human serum, and cerebrospinal fluid in microfluidic chips. Protein recovery was investigated down to protein concentrations of 0.3 μg/mL. Recoveries of 90% were observed with total protein amounts of 10 ng, even for microfluidic channels up to 835 mm in length and with a cross section of 80 μm × 230 μm in a COC 6013/8007 foil. For comparison, only 30 and 60% of the protein was recovered in uncoated microfluidic channels with lengths of 835 and 128 mm, respectively. The long-term stability of the hydrophobin-coated chips for 8 weeks was demonstrated. F. Schlenker, E. Kipf, N. Borst, N. Paust, R. Zengerle, F. von Stetten, P. Juelg, T. HutzenlaubCentrifugal Microfluidic Integration of 4-Plex ddPCR
Demonstrated by the Quantification of Cancer-Associated
Point Mutations 2021 Processes , volume : 2021, issue : 9, supplement : 97» show abstract « hide abstract Abstract We present the centrifugal microfluidic implementation of a four-plex digital droplet
polymerase chain reaction (ddPCR). The platform features 12 identical ddPCR units on a LabDisk
cartridge, each capable of generating droplets with a diameter of 82.7 +/- 9 µm. By investigating
different oil–surfactant concentrations, we identified a robust process for droplet generation and
stabilization. We observed high droplet stability during thermocycling and endpoint fluorescence
imaging, as is required for ddPCRs. Furthermore, we introduce an automated process for fourcolor
fluorescence imaging using a commercial cell analysis microscope, including a customized
software pipeline for ddPCR image evaluation. The applicability of ddPCRs is demonstrated by
the quantification of three cancer-associated KRAS point mutations (G12D, G12V and G12A) in a
diagnostically relevant wild type DNA background. The four-plex assay showed high sensitivity
(3.5–35 mutant DNA copies in 15,000 wild type DNA copies) and linear performance (R2 = 0.99)
across all targets in the LabDisk. T. Gross, C. Jeney, D. Halm, G. Finkenzeller, G. B. Stark, R. Zengerle, P. Koltay, S. ZimmermannCharacterization of CRISPR/Cas9 RANKL knockout mesenchymal stem cell clones based on single-cell printing technology and Emulsion Coupling assay as a low-cellularity workflow for single-cell cloning 2021 Plos One , volume : 16, issue : 3, page : e0238330» show abstract « hide abstract Abstract The homogeneity of the genetically modified single-cells is a necessity for many applications such as cell line development, gene therapy, and tissue engineering and in particular for regenerative medical applications. The lack of tools to effectively isolate and characterize CRISPR/Cas9 engineered cells is considered as a significant bottleneck in these applications. Especially the incompatibility of protein detection technologies to confirm protein expression changes without a preconditional large-scale clonal expansion creates a gridlock in many applications. To ameliorate the characterization of engineered cells, we propose an improved workflow, including single-cell printing/isolation technology based on fluorescent properties with high yield, a genomic edit screen (Surveyor assay), mRNA RT-PCR assessing altered gene expression, and a versatile protein detection tool called emulsion-coupling to deliver a high-content, unified single-cell workflow. The workflow was exemplified by engineering and functionally validating RANKL knockout immortalized mesenchymal stem cells showing bone formation capacity of these cells. The resulting workflow is economical, without the requirement of large-scale clonal expansions of the cells with overall cloning efficiency above 30% of CRISPR/Cas9 edited cells. Nevertheless, as the single-cell clones are comprehensively characterized at an early, highly parallel phase of the development of cells including DNA, RNA, and protein levels, the workflow delivers a higher number of successfully edited cells for further characterization, lowering the chance of late failures in the development process. D. Kainz, B. Breiner, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. PaustEliminating viscosity bias in lateral flow tests 2021 Microsystems & Nanoengineering , volume : 7, page : 72 S. Hin, B. Lopez-Jimena, M. Bakheit, V. Klein, S. Stack, C. Fall, A. Sall, K. Enan, M. Mustafa, V. Rusu, S. Goethel, N. Paust, R. Zengerle, L. Gillies, S. Frischmann, M. Weidmann, K. MitsakakisFully automated point-of-care differential diagnosis of acute febrile illness 2021 PLoS Negl. Trop. Dis. , volume : 15, issue : 2, page : e0009177» show abstract « hide abstract Abstract In this work, a platform was developed and tested to allow to detect a variety of candidate viral, bacterial and parasitic pathogens, for acute fever of unknown origin. The platform is based on a centrifugal microfluidic cartridge, the LabDisk (“FeverDisk” for the specific application), which integrates all necessary reagents for sample-to-answer analysis and is processed by a compact, point-of-care compatible device... M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. Homann, F. von Stetten, R. Zengerle, N. PaustHigh Dynamic Range Digital Assay Enabled by Dual-Volume Centrifugal Step Emulsification 2021 Analytical Chemistry , volume : 93, issue : 5, pages : 2854 - 2860» show abstract « hide abstract Abstract We implement dual-volume centrifugal step emulsification on a single chip to extend the dynamic range of digital assays. Compared to published single-volume approaches, the range between the lower detection limit (LDL) and the upper limit of quantification (ULQ) increases by two orders of magnitude. In comparison to existing multivolume approaches, the dual-volume centrifugal step emulsification requires neither complex manufacturing nor specialized equipment. Sample metering into two subvolumes, droplet generation, and alignment of the droplets in two separate monolayers are performed automatically by microfluidic design. Digital quantification is demonstrated by exemplary droplet digital loop-mediated isothermal amplification (ddLAMP). Within 5 min, the reaction mix is split into subvolumes of 10.5 and 2.5 μL, and 2,5k and 176k droplets are generated with diameters of 31.6 ± 1.4 and 213.9 ± 7.5 μm, respectively. After 30 min of incubation, quantification over 5 log steps is demonstrated with a linearity of R2 ≥ 0.992. H. Nguyen, F. Lombeck, C. Schwarz, P. A. Heizmann, M. Adamski, H-F. Lee, B. Britton, S. Holdcroft, S. Vierrath, M. BreitwieserHydrocarbon-based Pemion™ proton exchange membrane fuel cells with state-of-the-art performance 2021 Sustainable Energy and Fuels , volume : 5, pages : 3687 - 3699» show abstract « hide abstract Abstract Non-fluorinated hydrocarbon ionomers feature distinct technical, cost, and environmental advantages over incumbent perfluorinated sulfonic acid (PFSA)-based ionomers: they offer improved thermo-mechanical properties at temperatures beyond 90 °C, likelihood of lower material cost, lower gas cross-over, and facile recycling of platinum group metals. In addition, fluorine-free hydrocarbon ionomers are less hazardous to the environment owing to the lack of (per)fluorinated precursors. Yet, the performance of hydrogen fuel cells with hydrocarbon-based ionomers and membranes has been historically largely inferior to the PFSA-based state of the art. In this study, we present wholly hydrocarbon fuel cells exceeding previous literature landmarks by a factor of nearly two, with peak power densities of 2.1 W cm−2 under H2/O2 (atmospheric pressure and 95% relative humidity), and 1.1 W cm−2 under H2/air (250 kPaabs and 50% relative humidity). This improvement was achieved by the use of Pemion™ – a sulfo-phenylated polyphenylene-based cation exchange material – as ionomer in the catalyst layer and as proton exchange membrane with a low thickness of 7 μm, and an optimization of cathode catalyst layer based on PtCo/C. Based on an in-depth study of electrochemical performance under various conditions vs. a state-of-the-art PFSA reference cell, the performances of Pemion™-based cells were found to be more sensitive to changes in relative humidity of inlet gases, but the detrimental influence of high temperatures on performance was significantly reduced. At an operation temperature of 110 °C, 250 kPaabs, and 50% relative humidity, the peak power density (0.96 W cm−2) was 8% higher than the short-side chain PFSA-based reference cell (0.89 W cm−2), highlighting the potential of Pemion™ for next-generation fuel cells for heavy-duty or aeronautic applications. J.-N. Klatt, I. Schwarz, T. Hutzenlaub, R. Zengerle, F. Schwemmer, D. Kosse, J. Vincent, M. Scaer, K. Franaszczuk, D. Wadsworth, N. PaustMiniaturization, Parallelization, and Automation of Endotoxin Detection by Centrifugal Microfluidics 2021 Analytical Chemistry , volume : 93, issue : 24» show abstract « hide abstract Abstract We demonstrate microfluidic automation and parallelization of Limulus amebocyte lysate (LAL)-based bacterial endotoxin testing using centrifugal microfluidics. LAL is the standard reagent to test for endotoxin contaminations in injectable pharmaceuticals. The main features of the introduced system are more than 90% reduction of LAL consumption, from 100 μL/reaction to 9.6 μL/reaction, automated liquid handling to reduce opportunities for contamination and manual handling errors, and microfluidic parallelization by integrating 104 reactions into a single centrifugal microplate. In a single Eclipse microplate, 21 samples and their positive product controls are tested in duplicate. In addition, a standard curve with up to five points is generated, resulting in a total of 104 reactions. Test samples with a defined concentration of 0.5 endotoxin units per milliliter were tested, resulting in a coefficient of variation below 0.75%. A key feature for achieving a small coefficient of variation is ensuring the same path length along the microfluidic channels to the final reaction chambers for each sample and the reagent, so that any unspecific adsorption to the polymer surfaces does not affect the accuracy and precision. Analysis of a sample containing naturally occurring endotoxin with the developed microfluidic microplate yielded comparable results to the conventional testing method. A test with eight commercially available pharmaceuticals was found to pass all requirements for bacterial endotoxin testing as specified in the United States Pharmacopeia. The automated endotoxin testing system reveals specific advantages of centrifugal microfluidics for analytical biochemistry applications. Small liquid volumes are handled (metered, mixed, and aliquoted) in a very precise, highly integrated, and highly parallel manner within mass-fabricated microplates. K. MitsakakisNovel lab-on-a-disk platforms: a powerful tool for molecular fingerprinting of oral and respiratory tract infections 2021 Expert Rev. Mol. Diagn. , volume : 21, issue : 6, pages : 523 - 526 B. Johannsen, M. Karpíšek, D. Baumgartner, V. Klein, N. Bostanci, N. Paust, S. M. Früh, R. Zengerle, K. MitsakakisOne-step, wash-free, bead-based immunoassay employing bound-free phase detection 2021 Analytica Chimica Acta , volume : 1153, page : 338280» show abstract « hide abstract Abstract We present a simple and fast one-step heterogeneous immunoassay, with performance characteristics that can enable easy and versatile adaptation to miniaturized, automated point-of-care systems. This novel analytical method uses magnetic and fluorescent beads as capture and detection agents respectively. Its main feature is the measurement of the fluorescent signal in the bound-free phase for (semi-)quantitative detection of analytes. Thus, no washing is required and the workflow consists only of sample and reagent supply, incubation, separation and detection. The immunoassay concept is demonstrated with C-reactive protein (CRP), a systemic inflammation marker. CRP in only 5 μL of undiluted serum was measured in the range 20-140 mg L-1 (includes clinically relevant cut-off values). The limit of detection (LOD) was 22.1 ± 6.3 mg L-1 (incubation 15 min). A CRP certified reference material was measured on five different days. Intra- and inter-assay coefficients of variation were 4.6 % ± 1.9 % and 5.6 % respectively. To demonstrate the compatibility of the assay concept with additional matrices and concentration ranges, three oral inflammation markers, namely matrix metalloproteinases 8 and 9 (MMP-8, MMP-9) and tissue inhibitor of metalloproteinases 1 (TIMP-1), were measured in saliva in the ranges 0.47-30 ng mL-1 for MMP-8 and MMP-9, and 0.69-44 ng mL-1 for TIMP-1. LODs were 0.24 ng mL-1, 0.38 ng mL-1 and 0.39 ng mL-1 respectively (incubation 20 min). Multiplexing capacity of the assay concept was also shown with these markers. The demonstrated excellent reproducibility of the results, combined with the versatility and low complexity of the introduced immunoassay concept, make it an attractive candidate for applied analytical chemistry and automated point-of-care testing. F. Koch, O. Thaden, K. Tröndle, R. Zengerle, S. Zimmermann, P. KoltayOpen-source hybrid 3D-bioprinter for simultaneous printing of thermoplastics and hydrogels 2021 HardwareX , volume : 10, page : e00230 D. Baumgartner, B. Johannsen, M. Specht, J. Lüddecke, M. Rombach, S. Hin, N. Paust, F. von Stetten, R. Zengerle, C. Herz, J. R. Peham, P. N. Paqué, T. Attin, J. S. Jenzer, P. Körner, P. R. Schmidlin, T. Thurnheer, F. J. Wegehaupt, W. E. Kaman, A. Stubbs, J. P. Hays, V. Rusu, A. Michie, T. Binsl, D. Stejskal, M. Karpíšek, K. Bao, N. Bostanci, G. N. Belibasakis, K. MitsakakisOralDisk: A Chair-Side Compatible Molecular Platform Using Whole Saliva for Monitoring Oral Health at the Dental Practice 2021 Biosensors , volume : 11, issue : 11, page : 423 B. Shanahan, B. Britton, A. Belletti, S. Vierrath, M. BreitwieserPerformance and stability comparison of Aemion™ and Aemion+™ membranes for vanadium redox flow batteries 2021 RSC Advances , volume : 11, issue : 22, pages : 13077 - 13084» show abstract « hide abstract Abstract Anion exchange membranes (AEMs) have shown a significant rise in performance and durability within recent years for applications such as electrolysis and fuel cells. However, in vanadium redox-flow batteries, their use is of particular interest to lower costs and self-discharge rates compared to conventional perfluorinated sulfonic acid-based ionomers such as Nafion. In this work we evaluate the properties of two commercial AEMs, Aemion™ and Aemion+™, based on ex situ characterizations, an accelerated stress test degradation study (>1000 hours storage in highly oxidizing VO2+ electrolyte at 35 °C) and electrochemical battery cycle tests. All membranes feature low ionic resistances of below 320 mΩ cm2, enabling battery cycling at 100 mA cm−2. Aemion shows considerable VO2+ formation within a VO2+ stress test, whereas Aemion+ remains almost unaffected in the 1058 h stress test. Evaluating self-discharge data, cycling performance and durability data, Aemion+™ (50 μm thickness) features the best properties for vanadium redox-flow battery operation. L. Becherer, J. F. Hess, S. Frischmann, M. Bakheit, H. Nitschko, S. Stinco, F. Zitz, H. Hofer, G. Porro, F. Hausladen, K. Stock, D. Drossart, H. Wurm, H. Kuhn, D. Huber, T. Hutzenlaub, N. Paust, M. Keller, O. Strohmeier, S. Wadle, N. Borst, R. Zengerle, F. von StettenPoint-of-Care System for HTLV-1 Proviral Load Quantification by Digital Mediator Displacement LAMP 2021 Micromachines , volume : 12, issue : 2, page : 159» show abstract « hide abstract Abstract This paper presents a universal point-of-care system for fully automated quantification of human T-cell lymphotropic virus type 1 (HTLV-1) proviral load, including genomic RNA, based on digital reverse RNA transcription and c-DNA amplification by MD LAMP (mediator displacement loop-mediated isothermal amplification). A disposable microfluidic LabDisk with pre-stored reagents performs automated nucleic acid extraction, reaction setup, emulsification, reverse transcription, digital DNA amplification, and quantitative fluorogenic endpoint detection with universal reporter molecules. Automated nucleic acid extraction from a suspension of HTLV-1-infected CD4+ Tlymphocytes (MT-2 cells) yielded 8 +/- 7 viral nucleic acid copies per MT-2 cell, very similar to the manual reference extraction (7 +/- 2 nucleic acid copies). Fully automated sample processing from whole blood spiked with MT-2 cells showed a comparable result of 7 +/- 3 copies per MT-2 cell after a run time of two hours and 10 min. A. Brunauer, R. D. Verboket, D. M. Kainz, F. von Stetten, S. M. FrühRapid Detection of Pathogens in Wound Exudate via Nucleic Acid Lateral Flow Immunoassay 2021 Biosensors , volume : 11, issue : 3, page : 74» show abstract « hide abstract Abstract The rapid detection of pathogens in infected wounds can significantly improve the clinical outcome. Wound exudate, which can be collected in a non-invasive way, offers an attractive sample material for the detection of pathogens at the point-of-care (POC). Here, we report the development of a nucleic acid lateral flow immunoassay for direct detection of isothermally amplified DNA combined with fast sample preparation. The streamlined protocol was evaluated using human wound exudate spiked with the opportunistic pathogen Pseudomonas aeruginosa that cause severe health issues upon wound colonization. A detection limit of 2.1 × 105 CFU per mL of wound fluid was achieved, and no cross-reaction with other pathogens was observed. Furthermore, we integrated an internal amplification control that excludes false negative results and, in combination with the flow control, ensures the validity of the test result. The paper-based approach with only three simple hands-on steps has a turn-around time of less than 30 min and covers the complete analytical process chain from sample to answer. This newly developed workflow for wound fluid diagnostics has tremendous potential for reliable pathogen POC testing and subsequent target-oriented therapy. B. Shanahan, K. Seteiz, P. A. Heizmann, S. Koch, J. Büttner, S. Ouardi, S. Vierrath, A. Fischer, M. BreitwieserRapid wet-chemical oxidative activation of graphite felt electrodes for vanadium redox flow batteries 2021 RSC Advances , volume : 11, issue : 51, pages : 32095 - 32105 A. Lux, H. Bott, N. P. Malek, R. Zengerle, T. Maucher, J. Hoffmann, 1Real-Time Detection of Tumor Cells during Capture on a Filter Element Significantly Enhancing Detection Rate 2021 Biosensors , volume : 11, issue : 9, page : 312 P.N. Paqué, C. Herz, D.B. Wiedemeier, K. Mitsakakis, T. Attin, K. Bao, G.N. Belibasakis, J.P. Hays, J.S. Jenzer, W.E Kaman, M. Karpíšek, P. Körner, J.R. Peham, P.R. Schmidlin, T. Thurnheer, F.J. Wegehaupt, N. BostanciSalivary Biomarkers for Dental Caries Detection and Personalized Monitoring 2021 J. Pers. Med. , volume : 11, issue : 3, page : 235» show abstract « hide abstract Abstract This study investigated the potential of salivary bacterial and protein markers for evaluating the disease status in healthy individuals or patients with gingivitis or caries. Saliva samples from caries- and gingivitis-free individuals (n = 18), patients with gingivitis (n = 17), or patients with deep caries lesions (n = 38) were collected and analyzed for 44 candidate biomarkers (cytokines, chemokines, growth factors, matrix metalloproteinases, a metallopeptidase inhibitor, proteolytic enzymes, and selected oral bacteria). The resulting data were subjected to principal component analysis and used as a training set for random forest (RF) modeling. This computational analysis revealed four biomarkers (IL-4, IL-13, IL-2-RA, and eotaxin/CCL11) to be of high importance for the correct depiction of caries in 37 of 38 patients. The RF model was then used to classify 10 subjects (five caries-/gingivitis-free and five with caries), who were followed over a period of six months. The results were compared to the clinical assessments of dental specialists, revealing a high correlation between the RF prediction and the clinical classification. Due to the superior sensitivity of the RF model, there was a divergence in the prediction of two caries and four caries-/gingivitis-free subjects. These findings suggest IL-4, IL-13, IL-2-RA, and eotaxin/CCL11 as potential salivary biomarkers for identifying noninvasive caries. Furthermore, we suggest a potential association between JAK/STAT signaling and dental caries onset and progression. S. M. Früh, U. Matti, P. R. Spycher, M. Rubini, S. Lickert, T. Schlichthaerle, R. Jungmann, V. Vogel, J. Ries, I. SchoenSite-Specifically-Labeled Antibodies for Super-Resolution Microscopy Reveal In Situ Linkage Errors 2021 ACS Nano , volume : 15, issue : 7, pages : 12161 - 12170» show abstract « hide abstract Abstract The precise spatial localization of proteins in situ by super-resolution microscopy (SRM) demands their targeted labeling. Positioning reporter molecules as close as possible to the target remains a challenge in primary cells or tissues from patients that cannot be easily genetically modified. Indirect immunolabeling introduces relatively large linkage errors, whereas site-specific and stoichiometric labeling of primary antibodies relies on elaborate chemistries. In this study, we developed a simple two-step protocol to site-specifically attach reporters such as fluorophores or DNA handles to several immunoglobulin G (IgG) antibodies from different animal species and benchmarked the performance of these conjugates for 3D STORM (stochastic optical reconstruction microscopy) and DNA-PAINT (point accumulation in nanoscale topography). Glutamine labeling was restricted to two sites per IgG and saturable by exploiting microbial transglutaminase after removal of N-linked glycans. Precision measurements of 3D microtubule labeling shell dimensions in cell lines and human platelets showed that linkage errors from primary and secondary antibodies did not add up. Monte Carlo simulations of a geometric microtubule-IgG model were in quantitative agreement with STORM results. The simulations revealed that the flexible hinge between Fab and Fc segments effectively randomized the direction of the secondary antibody, while the restricted binding orientation of the primary antibody’s Fab fragment accounted for most of the systematic offset between the reporter and α-tubulin. DNA-PAINT surprisingly yielded larger linkage errors than STORM, indicating unphysiological conformations of DNA-labeled IgGs. In summary, our cost-effective protocol for generating well-characterized primary IgG conjugates offers an easy route to precise SRM measurements in arbitrary fixed samples. M. Drews, J. Büttner, M. Bauer, J. Ahmed, R. Sahu, S. Vierrath, C. Scheu, A. Fischer, D. BiroSpruce Hard Carbon Anodes for Lithium-Ion Batteries 2021 ChemElectroChem , volume : 8, pages : 4750 - 4761 F. Schlenker, E. Kipf, M. Deuter, I. Höffkes, M. Lehnert, R. Zengerle, F von Stetten, F. Scherer, J. Wehrle, N. von Bubnoff, P. Juelg, T. Hutzenlaub, N. BorstStringent Base Specific and Optimization-Free Multiplex Mediator Probe ddPCR for the Quantification of Point Mutations in Circulating Tumor DNA 2021 cancers , volume : 13, issue : 22, page : 5742 P. Juelg, E. Kipf, M. Specht, M. Fillies, C. Eckert, N. Paust, R. Zengerle, M. Lehnert, T. HutzenlaubThe MRD disk: automated minimal residual disease monitoring by highly sensitive centrifugal microfluidic multiplex qPCR 2021 Lab Chip , volume : 21, pages : 558 - 570» show abstract « hide abstract Abstract We present a proof-of-principle study on automated, highly sensitive and multiplexed qPCR quantification by centrifugal microfluidics. The MRD disk can be used for standardisation of repetitive, longitudinal assays with high requirements on reproducibility and sensitivity, such as cancer monitoring. In contrast to high-throughput qPCR automation by bulky and expensive robotic workstations we employ a small centrifugal microfluidic instrument, addressing the need of low- to mid-throughput applications. As a potential application we demonstrate automated minimum residual disease (MRD) monitoring of prognostic markers in patients with acute lymphoblastic leukaemia (ALL). The disk-workflow covers all aspects of clinical gold standard MRD quantification: generation of standard curves, specificity controls, no template controls and quantification of the ALL patient sample. We integrated a highly sensitive, colorimetric 2-plex analysis of MRD targets, as well as a 2-plex analysis of reference genes, both in parallel and in a single LabDisk cartridge. For this purpose, a systematic procedure for crosstalk- and signal-to-noise-optimisation is introduced, providing a guideline for efficient multiplex readout inside microfluidic platforms. The qPCR standard curves (n = 12/12) generated on-disk reach clinically required linearity (R2 = 98.1% to R2 = 99.8%). In three consecutive MRD disk runs with an ALL patient sample containing the two representative MRD targets VH3D3D5JH3 and VkIkde, we observe high accordance between the on-disk quantifications (48 ± 6 copies/reaction and 69 ± 6 copies/reaction) and the expected concentrations (57 copies/reaction for both targets). In comparison to the clinical gold standard of manually pipetted, singleplex assays, the MRD disk yields comparable limit of quantification (1 × 10−4) in n = 6/6 analyses (vs. n = 4/4 in gold standard) and a limit of detection (1 × 10−5) in n = 6/6 analysis (vs. n = 2/4 in gold standard). The automation reduces the risk of manual liquid handling errors, making the MRD disk an attractive solution to assure reproducibility in moderate-throughput, longitudinal gene quantification applications. S. Koch, P. A. Heizmann, S. K. Kilian, B. Britton, S. Holdcroft, M. Breitwieser, S. VierrathThe effect of ionomer content in catalyst layers in anion-exchange membrane water electrolyzers prepared with reinforced membranes (Aemion+™) 2021 J. Mater. Chem. A , volume : 9, pages : 15744 - 15754 M. Tsagiopoulou, M. C. Maniou, N. Pechlivanis, A. Togkousidis, M. Kotrová, T. Hutzenlaub, I. Kappas, A. Chatzidimitriou, F. PsomopoulosUMIc: A Preprocessing Method for UMI Deduplication and Reads Correction 2021 Front. Genet. , volume : May, 28 N. Bostanci, K. Mitsakakis, B. Afacan, K. Bao, B. Johannsen, D. Baumgartner, L. Müller, H. Kotolová, G. Emingil, M. KarpíšekValidation and verification of predictive salivary biomarkers for oral health 2021 Scientific Reports , volume : 11, page : 6406» show abstract « hide abstract Abstract Oral health is important not only due to the diseases emerging in the oral cavity but also due to the direct relation to systemic health. Thus, early and accurate characterization of the oral health status is of utmost importance. There are several salivary biomarkers as candidates for gingivitis and periodontitis, which are major oral health threats, affecting the gums. These need to be verified and validated for their potential use as differentiators of health, gingivitis and periodontitis status, before they are translated to chair-side for diagnostics and personalized monitoring. We aimed to measure 10 candidates using high sensitivity ELISAs in a well-controlled cohort of 127 individuals from three groups: periodontitis (60), gingivitis (31) and healthy (36). The statistical approaches included univariate statistical tests, receiver operating characteristic curves (ROC) with the corresponding Area Under the Curve (AUC) and Classification and Regression Tree (CART) analysis. The main outcomes were that the combination of multiple biomarker assays, rather than the use of single ones, can offer a predictive accuracy of > 90% for gingivitis versus health groups; and 100% for periodontitis versus health and periodontitis versus gingivitis groups. Furthermore, ratios of biomarkers MMP-8, MMP-9 and TIMP-1 were also proven to be powerful differentiating values compared to the single biomarkers F. Schlenker, E. Kipf, N. Borst, T. Hutzenlaub, R. Zengerle, F. von Stetten, P. JuelgVirtual Fluorescence Color Channels by Selective Photobleaching in Digital PCR Applied to the Quantification of KRAS Point Mutations 2021 Analytical Chemistry , volume : 93, issue : 30, pages : 10538 - 10545» show abstract « hide abstract Abstract Multiplexing of analyses is essential to reduce sample and reagent consumption in applications with large target panels. In applications such as cancer diagnostics, the required degree of multiplexing often exceeds the number of available fluorescence channels in polymerase chain reaction (PCR) devices. The combination of photobleaching-sensitive and photobleaching-resistant fluorophores of the same color can boost the degree of multiplexing by a factor of 2 per channel. The only additional hardware required to create virtual fluorescence color channels is a low-cost light-emitting diode (LED) setup for selective photobleaching. Here, we present an assay concept for fluorescence color multiplexing in up to 10 channels (five standard channels plus five virtual channels) using the mediator probe PCR with universal reporter (UR) fluorogenic oligonucleotides. We evaluate the photobleaching characteristic of 21 URs, which cover the whole spectral range from blue to crimson. This comprehensive UR data set is employed to demonstrate the use of three virtual channels in addition to the three standard channels of a commercial dPCR device (blue, green, and red) targeting cancer-associated point mutations (KRAS G12D and G12V). Moreover, a LOD (limit of detection) analysis of this assay confirms the high sensitivity of the multiplexing method (KRAS G12D: 16 DNA copies/reaction in the standard red channel and KRAS G12V: nine DNA copies/reaction in the virtual red channel). Based on the presented data set, optimal fluorogenic reporter combinations can be easily selected for the application-specific creation of virtual channels, enabling a high degree of multiplexing at low optical and technical effort. back to the year overview C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K.-D. Kreuer, S. VierrathAll-Hydrocarbon MEA for PEM Water Electrolysis Combining Low Hydrogen Crossover and High Efficiency 2020 Adv Energy Mater , page : 1903995» show abstract « hide abstract Abstract Hydrocarbon ionomers bear the potential to significantly lower the material cost and increase the efficiency of proton-exchange membrane water electrolyzers (PEMWE). However, no fully hydrocarbon membrane electrode assembly (MEA) with a performance comparable to Nafion-MEAs has been reported. PEMWE-MEAs are presented comprising sPPS as membrane and electrode binder reaching 3.5 A cm−2 at 1.8 V and thus clearly outperforming state-of-the-art Nafion-MEAs (N115 as membrane, 1.5 A cm−2 at 1.8 V) due to a significantly lower high frequency resistance (57 ± 4 mΩ cm² vs 161 ± 7 mΩ cm²). Additionally, pure sPPS-membranes show a three times lower gas crossover (<0.3 mA cm−2) than Nafion N115-membranes (>1.1 mA cm−2) in a fully humidified surrogate test. Furthermore, more than 80 h of continuous operation is shown for sPPS-MEAs in a preliminary durability test (constant current hold at 1 A cm−2 at 80 °C). These results rely on the unique transport properties of sulfonated poly(phenylene sulfone) (sPPS) that combines high proton conductivity with low gas crossover. D. Podbiel, R. Zengerle, J. HoffmannAn analytical model for void-free priming of microcavities 2020 Microfluid Nanofluid , volume : 24, issue : 16» show abstract « hide abstract Abstract The present work deals with the microfluidic evolution of capillary surfaces that are formed during the priming of microcavity structures with a non-wetting liquid. Due to the large contact angle of the priming liquid, a trapping of air within the microcavities poses a major impediment to a complete filling. We tackle this issue by developing a two-dimensional analytical model describing the geometrical shape of capillary surfaces formed in microcavity structures. In particular, the model is employed to derive two quantitative conditions for a void-free priming of a microcavity structure in terms of its aspect ratio, rounding parameters and the channel width. Microfluidic experiments are performed to verify the analytical results. Finally, we make use of the model to demonstrate a pressure-driven aliquoting of a non-wetting sample liquid in a flow chamber with an array of 55 microcavities by introducing a second immiscible liquid acting as a sealant. In this way, our work constitutes a basis for the design of microcavity-based liquid aliquoting structures that are used in various fields of application like PCR arrays, cell culture chips or digital reaction arrays. J. F. Hess, M. Kotrová, S. Calabrese, N. Darzentas, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. PaustAutomation of amplicon-based library preparation for next generation sequencing by centrifugal microfluidics 2020 Anal Chem , volume : 92, issue : 19, pages : 12833 - 12841» show abstract « hide abstract Abstract Next generation sequencing has become a mainstream method in bioanalysis. Improvements in sequencing and bioinformatics turned the complex and cumbersome library preparation to the bottle neck in terms of reproducibility and costs in the complete NGS workflow. Here, we introduce an automated library preparation approach based on a generic centrifugal microfluidic car-tridge. Multiplex polymerase chain reaction amplification and subsequent clean-up were processed with all reagents pre-stored on disk, including cell line-based DNA as quality control. Exchange of pre-stored reagents allows to apply the cartridge to different target genes. Sequencing of automatically prepared libraries from T-cell receptor and immunoglobulin gene rearrangements in context of lymphoproliferative disorders demonstrated excellent clean-up performance between 91.9% and 99.9% of target DNA reads and successful amplification of all target regions by up to 15 forward combined with four reverse primers. The fully auto-mated library preparation by centrifugal microfluidics thus offers attractive automation options in diagnostic settings. Z. Shu, M. Fechtig, F. Lombeck, M. Breitwieser, Roland Zengerle, Peter KoltayDirect Drop-on-Demand Printing of Molten Solder Bumps on ENIG Finishing at Ambient Conditions through StarJet Technology 2020 IEEE Access , volume : 8, pages : 210225 - 210233» show abstract « hide abstract Abstract In this paper, we report on a detailed experimental study carried out with the StarJet technology to investigate the mechanical adhesion properties of directly printed solder bumps on electroless nickel immersion gold (ENIG) plated PCB boards. The aim of this study is to determine the maximum bond strength achievable by this method and to find suitable printing parameters that allow for the production of reliable and consistent solder bumps by non-contact printing of molten solder (type SAC305). Molten solder droplets of about 250 μm diameter were printed at melt temperatures between 250 and 400 °C onto ENIG surfaces kept at temperatures in the range of 100 to 200 °C. Using shear force tests, the adhesion of the printed bumps was investigated as a function of the main process parameters: 1. printhead temperature, 2. substrate temperature, and 3. substrate preheating time. The formation of an intermetallic compound (IMC) between the solder and the ENIG was confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) measurements. As a result of the comprehensive experimental parameter study, suitable printing parameters for establishing bond strengths corresponding to maximum shear force values of 3000 to 4000 mN could be found, i.e. high printhead temperature of 400 °C, short preheating and time of < 2 min, and substrate heating at 180 °C The use of flux was found to slightly improve the bond strength and to improve the consistency of the printing results for extended operation times. The achieved high bond strength and the reasonable reproducibility of the printing results qualify the StarJet technology for further investigations regarding applications in the field of direct soldering of microelectronic chips and devices to PCB boards as well as other micro-assembly tasks in the future. F. Hegge, F. Lombeck, E. Cruz Ortiz, L. Bohn, M. von Holst, M. Kroschel, J. Hübner, M. Breitwieser, P. Strasser, S. VierrathEfficient and Stable Low Iridium Loaded Anodes for PEM Water Electrolysis Made Possible by Nanofiber Interlayers 2020 ACS Appl. Energy Mater , volume : 3, issue : 9, pages : 8276 - 8284» show abstract « hide abstract Abstract Significant reduction of the precious metal catalyst loading is one of the key challenges for the commercialization of proton-exchange membrane water electrolyzers. In this work we combine IrOx nanofibers with a conventional nanoparticle-based IrOx anode catalyst layer. With this hybrid design we can reduce the iridium loading by more than 80% while maintaining performance. In spite of an ultralow overall catalyst loading of 0.2 mgIr/cm2, a cell with a hybrid layer shows similar performance compared to a state-of-the-art cell with a catalyst loading of 1.2 mgIr/cm2 and clearly outperforms identically loaded reference cells with pure IrOx nanoparticle and pure nanofiber anodes. The improved performance is attributed to a combination of good electric contact and high porosity of the IrOx nanofibers with high surface area of the IrOx nanoparticles. Besides the improved performance, the hybrid layer also shows better stability in a potential cycling and a 150 h constant current test compared to an identically loaded nanoparticle reference. R. Moroni, S. ThieleFIB/SEM tomography segmentation by optical flow estimation 2020 Ultramicroscopy , volume : 219, page : 113090» show abstract « hide abstract Abstract Focused ion beam/scanning electron microscopy tomography (FIB/SEM tomography) is the method of choice for the tomographic reconstruction of mesoporous materials systems in various fields such as batteries, fuel cells, filter applications or composite materials. However, due to so called shine-through artifacts in FIB/SEM tomographies of porous materials, their segmentation into pore space and solid material is a nontrivial task. Here, an optical flow-based method that utilizes shine-through artifacts for segmentation is introduced. Subsequently, the performance of the method is discussed by means of tomographic datasets of a polymer electrolyte fuel cell catalyst layer and a lithium ion battery composite electrode. Previous, manual segmentations of these datasets allow the evaluation of the results – for the catalyst layer an accuracy of 86.6% and a precision of 84.0% is reached. In both cases, the optical flow-based approach gives significantly better results than comparable segmentations obtained from gray-value threshold binarization. P. Holzapfel, M. Bühler, D. Escalera-López, M. Bierling, F. Speck, K. Mayrhofer, S. Cherevko, C. V. Pham, S. ThieleFabrication of a Robust PEM Water Electrolyzer Based on Non-Noble Metal Cathode Catalyst: [Mo3S13]2− Clusters Anchored to N-Doped Carbon Nanotubes 2020 Small , page : 2003161» show abstract « hide abstract Abstract High investment costs and a dependence on noble metal catalysts currently
obstruct the large-scale implementation of proton exchange membrane water
electrolyzers (PEMWEs) for converting fluctuating green electricity into chemical
energy via water splitting. In this context, this work presents a high-performing
and stable non-noble metal catalyst for the hydrogen evolution reaction (HER),
consisting of [Mo3S13]2− clusters supported on nitrogen doped carbon nanotubes
(NCNTs). Strikingly, a significant electrochemically induced activation
of the Mo3S13-NCNT catalyst at high current densities is observed in full cell
configuration, enabling a remarkable current density of 4 A cm−2 at a cell voltage
of 2.36 V. To the authors’ knowledge, this is the highest reported value to date
for a PEMWE full cell using a non-noble metal HER catalyst. Furthermore, only
a minor degradation of 83 μV h−1 is observed during a stability test of 100 h
constant current at 1 A cm−2, with a nearly unchanged polarization behavior
after the current hold. Catalyst stability and activity are additionally analyzed via
online dissolution measurements. X-ray photoelectron spectroscopy examination
of the catalyst before and after electrochemical application reveals a correlation
between the electrochemical activation occurring via electrodissolution
with changes in the molecular structure of the Mo3S13-NCNT catalyst. D. Podbiel, L. Boecking, H. Bott, J. Kassel, D. Czurratis, F. Laermer, R. Zengerle, J. HoffmannFrom CAD to microfluidic chip within one day: rapid prototyping of lab-on-chip cartridges using generic polymer parts 2020 J Micromech Microeng , volume : 30, issue : 11, page : 5012» show abstract « hide abstract Abstract We report on a novel rapid prototyping approach for the manufacturing of highly individualized lab-on-chip (LoC) cartridges from generic polymer parts by laser micromachining and laser welding. The approach allows an immediate implementation of microfluidic networks, components, and functionalities into an existing LoC platform without the need for an expensive and time-consuming fabrication of production tools like molds or masks. We comprehensively describe the individual process steps of the rapid prototyping procedure including a wet-chemical treatment for an easy and effective surface polishing of laser micromachined polymer parts. For laying out, we introduce a generalized diagrammatic description of microfluidic functional units in order to design application-specific cartridges for molecular diagnostic workflows. We demonstrate the usability of our prototyped cartridges by performing microfluidic experiments within. Due to the use of generic polymer parts, our rapid prototyping approach combines a high degree of freedom with an intrinsic compatibility to an established and highly developed LoC system. By enabling an experimental testing within one day, the rapid prototyping procedure shortens development cycles and boosts the evolution of microfluidic networks as well as the implementation of novel microfluidic components and functionalities. D. Podbiel, F. Laermer, R. Zengerle, J. HoffmannFusing MEMS technology with lab-on-chip: nanoliter-scale silicon microcavity arrays for digital DNA quantification and multiplex testing 2020 Microsyst Nanoeng , volume : 6, page : 82» show abstract « hide abstract Abstract We report on the development of a microfluidic multiplexing technology for highly parallelized sample analysis via quantitative polymerase chain reaction (PCR) in an array of 96 nanoliter-scale microcavities made from silicon. This PCR array technology features fully automatable aliquoting microfluidics, a robust sample compartmentalization up to temperatures of 95 °C, and an application-specific prestorage of reagents within the 25 nl microcavities. The here presented hybrid silicon–polymer microfluidic chip allows both a rapid thermal cycling of the liquid compartments and a real-time fluorescence read-out for a tracking of the individual amplification reactions taking place inside the microcavities. We demonstrate that the technology provides very low reagent carryover of prestored reagents < 6 × 10−2 and a cross talk rate < 1 × 10−3 per PCR cycle, which facilitate a multi-targeted sample analysis via geometric multiplexing. Furthermore, we apply this PCR array technology to introduce a novel digital PCR-based DNA quantification method: by taking the assay-specific amplification characteristics like the limit of detection into account, the method allows for an absolute gene target quantification by means of a statistical analysis of the amplification results. F. Koch, K. Tröndle, G. Finkenzeller, R. Zengerle, S. Zimmermann, P. KoltayGeneric method of printing window adjustment for extrusion-based 3D-bioprinting to maintain high viability of mesenchymal stem cells in an alginate-gelatin hydrogel 2020 Bioprinting , page : e00094» show abstract « hide abstract Abstract Over the last decade, bioprinting of artificial tissues has been developed into a significant field of research. With an increasing number of printing technologies and bioinks used in bioprinting, its complexity increases as both the printing technology and the properties of the bioink influence the cell biological functionality and printing accuracy of the printed tissue. Therefore, optimization of bioprinting processes often remains a challenge, which could be solved by a smart fine-tuning of the process parameters. We present a novel method to adjust the printing window for extrusion-based bioprinting on the basis of a two-step assessment to determine process parameters such as nozzle size, extrusion flow rate, and printing temperature. First, a suitable printing temperature is deduced from the bioink properties and second nozzle size and extrusion flow rate is selected in a way that the immediate cell damage after printing is reduced. For both steps only basic rheological properties of the bioinks need to be known as well as detailed knowledge of the cell survival in the bioink for different shear stresses.
This method is applied to an exemplary alginate-gelatin hydrogel to show how the printing temperature affects the achievable printing accuracy. For this bioink, viability of immortalized mesenchymal stem cells (iMSC) decreases with about 4% per thousand Pascal increase in maximum shear stress. For different combinations of flow rate, nozzle size and nozzle shape it is shown, that only the maximum shear stress experienced by the iMSCs influences average cell viability. Factors like flow rate, nozzle size and shape only play an indirect role by influencing the maximum shear stress and individually have no significant influence on cell viability.
The experimental results allow a direct adjustment of printing parameters for the presented combination of hydrogel and cell type but are not limited to it. For other bioinks, the described generic method can be easily used to systematically adjust the printing parameters. For this purpose, only the basic rheological properties and the influence of shear stress on cell survival need to be known and process parameters can be set concerning the respective application. Y.-T. Kao, T. S. Kaminski, W. Postek, J. Guzowski, K. Makuch, A. Ruszczak, F. von Stetten, R. Zengerle, P. GarsteckiGravity-driven microfluidic assay for digital enumeration of bacteria and for antibiotic susceptibility testing 2020 Lab Chip , volume : 20, pages : 54 - 63» show abstract « hide abstract Abstract The alarming dynamics of antibiotic-resistant infections calls for the development of rapid and point-of-care (POC) antibiotic susceptibility testing (AST) methods. Here, we demonstrated the first completely stand-alone microfluidic system that allowed the execution of digital enumeration of bacteria and digital antibiograms without any specialized microfluidic instrumentation. A four-chamber gravity-driven step emulsification device generated ∼2000 monodisperse 2 nanoliter droplets with a coefficient of variation of 8.9% of volumes for 95% of droplets within less than 10 minutes. The manual workload required for droplet generation was limited to the sample preparation, the deposition into the sample inlet of the chip and subsequent orientation of the chip vertically without an additional pumping system. The use of shallow chambers imposing a 2D droplet arrangement provided superior stability of the droplets against coalescence and minimized the leakage of the reporter viability dye between adjacent droplets during long-term culture. By using resazurin as an indicator of the growth of bacteria, we were also able to reduce the assay time to ∼5 hours compared to 20 hours using the standard culture-based test. G.N. Belibasakis, B. Lund, C. Krüger Weiner, B. Johannsen, D. Baumgartner, D. Manoil, M. Hultin, K. MitsakakisHealthcare Challenges and Future Solutions in Dental Practice: Assessing Oral Antibiotic Resistances by Contemporary Point-of-Care Approaches 2020 Antibiotics , volume : 9, page : 810» show abstract « hide abstract Abstract Antibiotic resistance poses a global threat, which is being acknowledged at several levels, including research, clinical implementation, regulation, as well as by the World Health Organization. In the field of oral health, however, the issue of antibiotic resistances, as well as of accurate diagnosis, is underrepresented. Oral diseases in general were ranked third in terms of expenditures among the EU-28 member states in 2015. Yet, the diagnosis and patient management of oral infections, in particular, still depend primarily on empiric means. On the contrary, on the global scale, the field of medical infections has more readily adopted the integration of molecular-based systems in the diagnostic, patient management, and antibiotic stewardship workflows. In this perspective review, we emphasize the clinical significance of supporting in the future antibiotic resistance screening in dental practice with novel integrated and point-of-care operating tools that can greatly support the rapid, accurate, and efficient administration of oral antibiotics.
Download file E.C. Ortiz, F. Hegge, M. Breitwieser, S. VierrathImproving the performance of proton exchange membrane water electrolyzers with low Ir-loaded anodes by adding PEDOT: PSS as electrically conductive binder 2020 Rsc Adv , volume : 10, issue : 62, pages : 37329 - 37927» show abstract « hide abstract Abstract Reducing the iridium catalyst loading in the anode of polymer electrolyte membrane electrolyzers is a major goal to bring down the cost. However, anodes with low Ir-loading can suffer from poor electrical connectivity and hence lower the efficiency of the electrolyzer. In this work, we replace parts of the Nafion binder in the anode with an electrically conductive polymer (poly-3,4-ethylenedioxythiophene and polystyrene sulfonate acid complex, PEDOT:PSS) to counter this effect. At the optimal 50 : 50 blend we achieve a 120 mV lower overpotential (2.02 V) at 3 A cm−2 compared to a pure Nafion reference (2.14 V). This corresponds to a 6% better efficiency. Ex situ resistivity measurements and high frequency resistance measurements indicate that the major cause for this improvement lies in the reduced electrical in-plane resistance due to the electrical conductivity of PEDOT:PSS. P. Veh, B. Britton, S. Holdcroft, R. Zengerle, S. Vierrath, M. BreitwieserImproving the water management in anion-exchange membrane fuel cells via ultra-thin, directly deposited solid polymer electrolyte 2020 Rsc Adv , volume : 10, pages : 8645 - 8652» show abstract « hide abstract Abstract Thin ionomer membranes are considered key to achieve high performances in anion exchange membrane fuel cells. However, the handling of unsupported anion exchange membranes with thicknesses below 15 μm is challenging. Typical pre-treatments of KOH-soaking, DI-water rinsing and/or wet assembly with sub-15 μm thin films are particularly problematic. In this work, we report configurations of membrane electrode assemblies with solid polymer electrolyte thicknesses equivalent to 3, 5 and 10 μm, made possible by direct coating of the ionomer onto gas diffusion electrodes (direct membrane deposition). The anion-conducting solid polymer electrolyte employed is hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), which is known for its high mechanical stability and low rate of gas crossover. By fabricating membrane-electrode-assemblies with PtRu/C anodes and Pt/C cathodes with a low precious metal loading of <0.3 mg cm−2, reproducible performances beyond 1 W cm−2 in H2/O2 atmosphere are achieved. The thin membranes enable excellent performance robustness towards changes in relative humidity, as well as low ionic resistances (<40 mOhm cm2). P. Rukavina, F. Koch, M. Wehrle, K. Tröndle, G. B. Stark, P. Koltay, S. Zimmermann, R. Zengerle, F. Lampert, S. Strassburg, G. Finkenzeller, F. SimunovicIn vivo evaluation of bioprinted prevascularized bone tissue 2020 Biotechnol Bioeng , pages : 1 - 10» show abstract « hide abstract Abstract Bioprinting can be considered as a progression of the classical tissue engineering approach, in which cells are randomly seeded into scaffolds. Bioprinting offers the advantage that cells can be placed with high spatial fidelity within three‐dimensional tissue constructs. A decisive factor to be addressed for bioprinting approaches of artificial tissues is that almost all tissues of the human body depend on a functioning vascular system for the supply of oxygen and nutrients. In this study, we have generated cuboid prevascularized bone tissue constructs by bioprinting human adipose‐derived mesenchymal stem cells (ASCs) and human umbilical vein endothelial cells (HUVECs) by extrusion‐based bioprinting and drop‐on‐demand (DoD) bioprinting, respectively. The computer‐generated print design could be verified in vitro after printing. After subcutaneous implantation of bioprinted constructs in immunodeficient mice, blood vessel formation with human microvessels of different calibers could be detected arising from bioprinted HUVECs and stabilization of human blood vessels by mouse pericytes was observed. In addition, bioprinted ASCs were able to synthesize a calcified bone matrix as an indicator of ectopic bone formation. These results indicate that the combined bioprinting of ASCs and HUVECs represents a promising strategy to produce prevascularized artificial bone tissue for prospective applications in the treatment of critical‐sized bone defects. M. Trotter, D. Juric, Z. Bagherian, N. Borst, K. Gläser, T. Meissner, F. von Stetten, A. ZimmermannInkjet-Printing of Nanoparticle Gold and Silver Ink on Cyclic Olefin Copolymer for DNA-Sensing Applications 2020 Sensors , volume : 20, issue : 5, page : 1333» show abstract « hide abstract Abstract Inkjet technology as a maskless, direct-writing technology offers the potential for structured deposition of functional materials for the realization of electrodes for, e.g., sensing applications. In this work, electrodes were realized by inkjet-printing of commercial nanoparticle gold ink on planar substrates and, for the first time, onto the 2.5D surfaces of a 0.5 mm-deep microfluidic chamber produced in cyclic olefin copolymer (COC). The challenges of a poor wetting behavior and a low process temperature of the COC used were solved by a pretreatment with oxygen plasma and the combination of thermal (130 °C for 1 h) and photonic (955 mJ/cm²) steps for sintering. By performing the photonic curing, the resistance could be reduced by about 50% to 22.7 μΩ cm. The printed gold structures were mechanically stable (optimal cross-cut value) and porous (roughness factors between 8.6 and 24.4 for 3 and 9 inkjet-printed layers, respectively). Thiolated DNA probes were immobilized throughout the porous structure without the necessity of a surface activation step. Hybridization of labeled DNA probes resulted in specific signals comparable to signals on commercial screen-printed electrodes and could be reproduced after regeneration. The process described may facilitate the integration of electrodes in 2.5D lab-on-a-chip systems. C. Van Pham, M. Bühler, J. Knöppel, M. Bierling, D. Seeberger, D. Escalera-López, K. Mayrhofer, S. Cherevko, S. ThieleIrO2 coated TiO2 core-shell microparticles advance performance of low loading proton exchange membrane water electrolyzers 2020 Applied Catalysis B: Environmental , volume : 269, page : 118762» show abstract « hide abstract Abstract Herein we present novel IrO2 coated TiO2 core-shell microparticles (IrO2@TiO2) as an oxygen evolution reaction catalyst. We compare the IrO2@TiO2 catalyst to commercial TiO2 supported IrO2 catalyst (IrO2/TiO2) and pure IrO2 catalyst powder. A stability analysis via on-line inductively coupled plasma mass spectrometry based on the S-number, a descriptor considering both energy efficiency and catalyst utilization efficiency, shows that the IrO2@TiO2 catalyst shows high potential for practical applications. This was further confirmed by full-cell tests showing superior performance of the IrO2@TiO2 catalyst with moderate and low loadings of 1.2 mgIr cm−2 and 0.4 mgIr cm−2, respectively. The core-shell catalyst is synthesized via facile route suitable for large quantities. Moreover, stable inks from the synthesized catalyst powder make this system appealing for large scale manufacturing of cells. Given the facile synthesis route, high activity, and good stability, the IrO2@TiO2 catalyst is potentially suitable for industry proton exchange membrane water electrolysis application. L. Becherer, N. Borst, M. Bakheit, S. Frischmann, R. Zengerle, F. von StettenLoop-mediated isothermal amplification (LAMP) – review and classification of methods for sequence-specific detection 2020 Anal Methods-uk , volume : 12, pages : 717 - 746» show abstract « hide abstract Abstract In the course of the last 20 years, isothermal nucleic acid amplification tests have emerged as an important diagnostic tool, not only for clinical applications, but also for food quality control and environmental monitoring. Loop-mediated isothermal amplification (LAMP) is well known for its robust and highly sensitive and specific amplification of target DNA, which is achieved by utilizing up to six primers. Moreover, LAMP excels through its isothermal and energy efficient amplification requirements, rendering it a prime candidate for low-cost diagnostics and analysis at the point of need. Recently, methods for sequence-specific detection have gained more importance because, unlike sequence-independent detection methods, they are highly specific towards the target DNA. In the last 13 years, a variety of sequence-specific methods have emerged, based on a very diverse range of sensing techniques, including optical, magnetic, piezoelectric, electrochemical and magnetoresistive sensing. To give structure to the diverse multitude of sequence-specific methods, we created a systematic classification and provide a critical comparative evaluation according to a catalogue of criteria (analytical performance, multiplexing, quantification and instrumental requirements). Fluorescence-based detection, making up half of the methods, can be processed on open platforms and satisfies all the criteria listed before. Instrumental requirements are discussed in terms of complexity, portability and fluidic cartridges. In addition, the technological readiness level and the kind of platform (open versus method-tailored) are evaluated, the latter playing an important role in the miniaturization and automation of operational process steps. We also observe an increase in the use of smartphone-integrated sensors to improve LAMP-based point-of-need testing. In summary, recent developments in methods for the sequence-specific detection of LAMP demonstrate high potential for many future applications. P.N. Paqué, C. Herz, J.S. Jenzer, D.B. Wiedemeier, T. Attin, N. Bostanci, G.N. Belibasakis, K. Bao, P. Körner, T. Fritz, J. Prinz, P.R. Schmidlin, T. Thurnheer, F.J. Wegehaupt, K. Mitsakakis, J.R. PehamMicrobial Analysis of Saliva to Identify Oral Diseases Using a Point-of-Care Compatible qPCR Assay 2020 J Clin Med , volume : 9, page : 2945» show abstract « hide abstract Abstract Oral health is maintained by a healthy microbiome, which can be monitored by state-of-the art diagnostics. Therefore, this study evaluated the presence and quantity of ten oral disease-associated taxa (P. gingivalis, T. forsythia, T. denticola, F. nucleatum, C. rectus, P. intermedia, A. actinomycetemcomitans, S. mutans, S. sobrinus, oral associated Lactobacilli) in saliva and their clinical status association in 214 individuals. Upon clinical examination, study subjects were grouped into healthy, caries and periodontitis and their saliva was collected. A highly specific point-of-care compatible dual color qPCR assay was developed and used to study the above-mentioned bacteria of interest in the collected saliva. Assay performance was compared to a commercially available microbial reference test. Eight out of ten taxa that were investigated during this study were strong discriminators between the periodontitis and healthy groups: C. rectus, T. forsythia, P. gingivalis, S. mutans, F. nucleatum, T. denticola, P. intermedia and oral Lactobacilli (p < 0.05). Significant differentiation between the periodontitis and caries group microbiome was only shown for S. mutans (p < 0.05). A clear distinction between oral health and disease was enabled by the analysis of quantitative qPCR data of target taxa levels in saliva. L. Becherer, S. Knauf, M. Marks, S. Lueert, S. Frischmann, N. Borst, F. von Stetten, S. Bieb, Y. Adu-Sarkodie, K. Asiedu, O. Mitjà, M. BakheitMultiplex Mediator Displacement Loop-Mediated Isothermal Amplification for Detection of Treponema pallidum and Haemophilus ducreyi 2020 Emerg Infect Dis , volume : 26, pages : 282 - 288 M. Schulz, S. Calabrese, F. Hausladen, H. Wurm, D. Drossart, K. Stock, A. M. Sobieraj, F. Eichenseher, M. J. Loessner, M. Schmelcher, A. Gerhardts, U. Goetz, M. Handel, A. Serr, G. Haecker, J. Li, M. Specht, P. Koch, M. Meyer, P. Tepper, R. Rother, M. Jehle, S. Wadle, R. Zengerle, F. von Stetten, N. Paust, N. BorstPoint-of-care testing system for digital single cell detection of MRSA directly from nasal swabs 2020 Lab Chip , volume : 20, pages : 2549 - 2561» show abstract « hide abstract Abstract We present an automated point-of-care testing (POCT) system for rapid detection of species- and resistance markers in methicillin-resistant Staphylococcus aureus (MRSA) at the level of single cells, directly from nasal swab samples. Our novel system allows clear differentiation between MRSA, methicillin-sensitive S. aureus (MSSA) and methicillin-resistant coagulase-negative staphylococci (MR-CoNS), which is not the case for currently used real-time quantitative PCR based systems. On top, the novel approach outcompetes the culture-based methods in terms of its short time-to-result (1 h vs. up to 60 h) and reduces manual labor. The walk-away test is fully automated on the centrifugal microfluidic LabDisk platform. The LabDisk cartridge comprises the unit operations swab-uptake, reagent pre-storage, distribution of the sample into 20 000 droplets, specific enzymatic lysis of Staphylococcus spp. and recombinase polymerase amplification (RPA) of species (vicK) – and resistance (mecA) -markers. LabDisk actuation, incubation and multi-channel fluorescence detection is demonstrated with a clinical isolate and spiked nasal swab samples down to a limit of detection (LOD) of 3 ± 0.3 CFU μl−1 for MRSA. The novel approach of the digital single cell detection is suggested to improve hospital admission screening, timely decision making, and goal-oriented antibiotic therapy. The implementation of a higher degree of multiplexing is required to translate the results into clinical practice. B. Johannsen, D. Mark, N. Boillat-Blanco, A. Fresco, D. Baumgartner, R. Zengerle, K. MitsakakisRapid diagnosis of respiratory tract infections using a point-of-care platform incorporating a clinical decision support algorithm 2020 Stud. in Health Technol. Inform , volume : 273, pages : 234 - 239» show abstract « hide abstract Abstract Respiratory Tract Infections (RTIs) are among the top reasons for visiting a General Practitioner (GP) and the main cause of unnecessary antibiotic prescriptions. Reducing inappropriate use is essential to decrease antibiotic resistance and adverse events. The goal of the Eurostars project “Respiotic” is to develop a new point-of-care (POC) platform based on the centrifugal microfluidic LabDisk that will detect the main responsible viruses and bacteria for community-acquired RTIs, including associated resistances and host biomarkers. The diagnostic platform will use a Polymerase Chain Reaction (PCR) and an immunoassay cartridge on the same instrument and provide the combined analysis within less than 1 h. An electronic clinical algorithm will co-assess the test results and act as a decision support tool for the GPs’ patient management and prescriptions. M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, L. Roux, T. Sutcliffe, J. Peham, C. Herz, M. Panning, O. Donoso Mantke, K. MitsakakisRespiDisk: a point-of-care platform for fully automated detection of respiratory tract infection pathogens in clinical samples 2020 Analyst , volume : 145, pages : 7040 - 7047» show abstract « hide abstract Abstract We present the RespiDisk enabling the fully automated and multiplex point-of-care (POC) detection of (currently) up to 19 respiratory tract infection (RTI) pathogens from a single sample based on reverse transcriptase polymerase chain reaction (RT-PCR). RespiDisk comprises a RTI-specific implementation of the centrifugal microfluidic LabDisk platform and combines new and existing advanced unit operations for liquid control, thereby automating all assay steps only by a spinning frequency and temperature protocol in combination with the use of a permanent magnet for in situ bead handing. The capabilities of the system were demonstrated with 36 tested quality samples mimicking clinical conditions (clinical and/or cultured material suspended in transport medium or synthetic bronchoalveolar lavage (BAL)) from past external quality assessment (EQA) panels covering 13 of the 19 integrated RTI detection assays. In total, 36 samples × 19 assays/sample resulting in 684 assays were performed with the RespiDisk, and its analytical performance was in full agreement with the routine clinical workflow serving as reference. A strong feature of the platform is its universality since its components allow the simultaneous detection of a broad panel of bacteria and viruses in a single run, thereby enabling the differentiation between antibiotic-treatable diseases. Furthermore, the full integration of all necessary biochemical components enables a reduction of the hands-on time from manual to automated sample-to-answer analysis to about 5 min. The study was performed on an air-heated LabDisk Player instrument with a time-to-result of 200 min. J. Riba, J. Schoendube, S. Zimmermann, P. Koltay, R. ZengerleSingle-cell dispensing and ‘realtime’cell classification using convolutional neural networks for higher efficiency in single-cell cloning 2020 nature scientific reports , volume : 10, page : 1193» show abstract « hide abstract Abstract Single-cell dispensing for automated cell isolation of individual cells has gained increased attention
in the biopharmaceutical industry, mainly for production of clonal cell lines. Here, machine learning
for classification of cell images is applied for ‘real-time’ cell viability sorting on a single-cell printer.
We show that an extremely shallow convolutional neural network (CNN) for classification of lowcomplexity
cell images outperforms more complex architectures. Datasets with hundreds of cell images
from four different samples were used for training and validation of the CNNs. The clone recovery,
i.e. the fraction of single-cells that grow to clonal colonies, is predicted to increase for all the samples
investigated. Finally, a trained CNN was deployed on a c.sight single-cell printer for ‘real-time’ sorting of
a CHO-K1 cells. On a sample with artificially damaged cells the clone recovery could be increased from
27% to 73%, thereby resulting in a significantly faster and more efficient cloning. Depending on the
classification threshold, the frequency at which viable cells are dispensed could be increased by up to
65%. This technology for image-based cell sorting is highly versatile and can be expected to enable cell
sorting by computer vision with respect to different criteria in the future. M. Drews, S. Tepner, P. Haberzettl, H. Gentischer, W. Beichel, M. Breitwieser, S. Vierrath, D. BiroTowards 3D-lithium ion microbatteries based on silicon/graphite blend anodes using a dispenser printing technique 2020 RSC Adv. , volume : 10, pages : 22440 - 22448» show abstract « hide abstract Abstract In this work we present for the first time high capacity silicon/carbon–graphite blend slurries designed for application in 3D-printed lithium ion microbatteries (3D-MLIBs). The correlation between electrochemical and rheological properties of the corresponding slurries was systematically investigated with the prospect of production by an automated dispensing process. A variation of the binder content (carboxymethyl cellulose/styrene–butadiene rubber, CMC/SBR) between 6 wt%, 12 wt%, 18 wt% and 24 wt% in the anode slurry proved to be crucial for the printing process. Regarding the rheological properties increasing binder content leads to increased viscosity and yield stress values promising printed structures with high aspect ratios. Consequently, interdigital 3D-printed micro anode structures with increasing aspect ratios were printed with increasing binder content. For printed 6-layer structures aspect ratios of 6.5 were achieved with anode slurries containing 24 wt% binder. Electrochemical results from planar coin cell measurements showed that anodes containing 12 wt% CMC/SBR binder content exhibited stable cycling at the highest charge capacities of 484 mA h g−1 at a current rate of C/4. Furthermore, at 4C the cells showed high capacity retention of 89% compared to cycling at C/4. Based on this study and the given material formulation we recommend 18 wt% CMC/SBR as the best trade-off between electrochemical and rheological properties for future work with fully 3D-printed MLIBs. J.-N. Klatt, M. Depke, N. Goswami, N. Paust, R. Zengerle, F. Schmidt, T. HutzenlaubTryptic digestion of human serum for proteomic mass spectrometry automated by centrifugal microfluidics 2020 Lab Chip , volume : 20, page : 2937» show abstract « hide abstract Abstract Mass spectrometry has become an important analytical tool for protein research studies to identify,
characterise and quantify proteins with unmatched sensitivity in a highly parallel manner. When transferred
into clinical routine, the cumbersome and error-prone sample preparation workflows present a major
bottleneck. In this work, we demonstrate tryptic digestion of human serum that is fully automated by
centrifugal microfluidics. The automated workflow comprises denaturation, digestion and acidification. The
input sample volume is 1.3 μl only. A triplicate of human serum was digested with the developed
microfluidic chip as well as with a manual reference workflow on three consecutive days to assess the
performance of our system. After desalting and liquid chromatography tandem mass spectrometry, a total
of 604 proteins were identified in the samples digested with the microfluidic chip and 602 proteins with
the reference workflow. Protein quantitation was performed using the Hi3 method, yielding a 7.6% lower
median intensity CV for automatically digested samples compared to samples digested with the reference
workflow. Additionally, 17% more proteins were quantitated with less than 30% CV in the samples from the
microfluidic chip, compared to the manual control samples. This improvement can be attributed to the
accurate liquid metering with all volume CVs below 1.5% on the microfluidic chip. The presented
automation solution is attractive for laboratories in need of robust automation of sample preparation from
small volumes as well as for labs with a low or medium throughput that does not allow for large
investments in robotic systems. S. Hin, D. Baumgartner, M. Specht, J. Lüddecke, E. M. Arjmand, B. Johannsen, L. Schiedel, M. Rombach, N. Paust, F. von Stetten, R. Zengerle, N. Wipf, P. Müller, K. Mavridis, J. Vontas, K. Mitsakakis, * Indicates equally contributing authorsVectorDisk: A Microfluidic Platform Integrating Diagnostic Markers for Evidence-Based
Mosquito Control
2020 Processes , volume : 8, issue : 12, page : 1677» show abstract « hide abstract Abstract Effective mosquito monitoring relies on the accurate identification and characterization of
the target population. Since this process requires specialist knowledge and equipment that is not
widely available, automated field-deployable systems are highly desirable. We present a centrifugal
microfluidic cartridge, the VectorDisk, which integrates TaqMan PCR assays in two feasibility studies,
aiming to assess multiplexing capability, specificity, and reproducibility in detecting disk-integrated
vector-related assays. In the first study, pools of 10 mosquitoes were used as samples. We tested
18 disks with 27 DNA and RNA assays each, using a combination of multiple microfluidic chambers
and detection wavelengths (geometric and color multiplexing) to identify mosquito and malaria
parasite species as well as insecticide resistance mechanisms. In the second study, purified nucleic
acids served as samples to test arboviral and malaria infective mosquito assays. Nine disks were tested
with 14 assays each. No false positive results were detected on any of the disks. The coeffcient of
variation in reproducibility tests was <10%. The modular nature of the platform, the easy adaptation
of the primer/probe panels, the cold chain independence, the rapid (2–3 h) analysis, and the assay
multiplexing capacity are key features, rendering the VectorDisk a potential candidate for automated
vector analysis. M. Schulz, S. Probst, S. Calabrese, A. Homann, N. Borst, M. Weiss, F. von Stetten, R. Zengerle, N. PaustVersatile Tool for Droplet Generation in Standard Reaction Tubes by Centrifugal Step Emulsification 2020 Molecules , volume : 25, issue : 8, page : 1914» show abstract « hide abstract Abstract We present a versatile tool for the generation of monodisperse water-in-fluorinated-oil droplets in standard reaction tubes by centrifugal step emulsification. The microfluidic cartridge is designed as an insert into a standard 2 mL reaction tube and can be processed in standard laboratory centrifuges. It allows for droplet generation and subsequent transfer for any downstream analysis or further use, does not need any specialized device, and manufacturing is simple because it consists of two parts only: A structured substrate and a sealing foil. The design of the structured substrate is compatible to injection molding to allow manufacturing at large scale. Droplets are generated in fluorinated oil and collected in the reaction tube for subsequent analysis. For sample sizes up to 100 µL with a viscosity range of 1 mPa·s–4 mPa·s, we demonstrate stable droplet generation and transfer of more than 6 × 105 monodisperse droplets (droplet diameter 66 µm ± 3 µm, CV ≤ 4%) in less than 10 min. With two application examples, a digital droplet polymerase chain reaction (ddPCR) and digital droplet loop mediated isothermal amplification (ddLAMP), we demonstrate the compatibility of the droplet production for two main amplification techniques. Both applications show a high degree of linearity (ddPCR: R2 ≥ 0.994; ddLAMP: R2 ≥ 0.998), which demonstrates that the cartridge and the droplet generation method do not compromise assay performance. C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K.-D. Kreuer, S. VierrathWater Electrolyzers: All‐Hydrocarbon MEA for PEM Water Electrolysis Combining Low Hydrogen Crossover and High Efficiency 2020 Adv Energy Mater » show abstract « hide abstract Abstract Hydrocarbon ionomers bear the potential to significantly lower the material cost and increase the efficiency of proton‐exchange membrane water electrolyzers (PEMWE). However, no fully hydrocarbon membrane electrode assembly (MEA) with a performance comparable to Nafion‐MEAs has been reported. PEMWE‐MEAs are presented comprising sPPS as membrane and electrode binder reaching 3.5 A cm−2 at 1.8 V and thus clearly outperforming state‐of‐the‐art Nafion‐MEAs (N115 as membrane, 1.5 A cm−2 at 1.8 V) due to a significantly lower high frequency resistance (57 ± 4 mΩ cm² vs 161 ± 7 mΩ cm²). Additionally, pure sPPS‐membranes show a three times lower gas crossover (<0.3 mA cm−2) than Nafion N115‐membranes (>1.1 mA cm−2) in a fully humidified surrogate test. Furthermore, more than 80 h of continuous operation is shown for sPPS‐MEAs in a preliminary durability test (constant current hold at 1 A cm−2 at 80 °C). These results rely on the unique transport properties of sulfonated poly(phenylene sulfone) (sPPS) that combines high proton conductivity with low gas crossover. back to the year overview B. Shanahan, T. Böhm, B. Britton, S. Holdcroft, R. Zengerle, S. Vierrath, S. Thiele, M. Breitwieser30 μm thin hexamethyl-p-terphenyl poly(benzimidazolium) anion exchange membrane for vanadium redox-flow batteries 2019 Electrochem Commun , volume : 102, pages : 37 - 40» show abstract « hide abstract Abstract We present the first results of an anion exchange ionomer membrane, hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), in a vanadium redox flow battery. Anion exchange membranes exhibit superior vanadium crossover suppression compared to proton exchange membranes due to the Gibbs–Donnan effect. HMT-PMBI was benchmarked against a similarly thin Nafion XL membrane which allowed us to compare differences based solely on chemical properties of the ionomer materials. We report cycling data of 45 cycles at a current density of 150 mA/cm2 with excellent coulombic efficiency of >99.4%, energy efficiency of 80.6–74.2% and a low ohmic resistance of 0.219–0.255 Ω cm2. In addition, a three times lower self-discharge rate is obtained for the HMT-PMBI membrane compared to Nafion XL. HMT-PMBI is therefore a potential alternative for PFSA based ionomers in VRFB applications. B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S. M. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. MitsakakisAutomated Pre-Analytic Processing of Whole Saliva Using Magnet-Beating for Point-of-Care Protein
Biomarker Analysis
2019 Micromachines , volume : 10, issue : 12, page : 833» show abstract « hide abstract Abstract Saliva offers many advantages for point-of-care (PoC) diagnostic applications due to non-invasive, easy, and cost-effective methods of collection. However, the complex matrix with its non-Newtonian behavior and high viscosity poses handling challenges. Several tedious and long pre-analytic steps, incompatible with PoC use, are required to liquefy and homogenize saliva samples before protein analysis can be performed. We apply magnet-beating to reduce hands-on time and to simplify sample preparation. A magnet in a chamber containing the whole saliva is actuated inside a centrifugal microfluidic cartridge by the interplay of centrifugal and magnetic forces. Rigorous mixing, which homogenizes the saliva sample, is then initiated. Consequently, fewer manual steps are required to introduce the whole saliva into the cartridge. After 4 min of magnet-beating, the processed sample can be used for protein analysis. The viscosity of whole saliva has been reduced from 10.4 to 2.3 mPa s. Immunoassay results after magnet-beating for three salivary periodontal markers (MMP-8, MMP-9, TIMP-1) showed a linear correlation with a slope of 0.99 when compared to results of reference method treated samples. Conclusively, magnet-beating has been shown to be a suitable method for the pre-analytic processing of whole saliva for fully automated PoC protein analysis. P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, M. Keller, T. Hutzenlaub, F. von Stetten, R. Zengerle, N. PaustAutomated serial dilutions for high-dynamic-range assays enabled by fill-level-coupled valving in centrifugal microfluidics 2019 Lab Chip , volume : 19, pages : 2205 - 2219» show abstract « hide abstract Abstract We introduce a new concept for centrifugal microfluidics that enables fully automated serial dilution generation without any additional means besides temperature control. Key feature is time-independent, serial valving of mixing chambers by fill-level-coupled temperature change rate (FLC-TCR) actuated valving. The automated dilution is realized under continuous rotation which enables reliable control of wetting liquids without the need of any additional fabrication steps such as hydrophobic coatings. All fluidic features are implemented in a monolithic fashion and disks are manufactured by foil thermoforming for scalable manufacturing. The new valving concept is demonstrated to reliably prevent valving if the diluted sample is not added to the mixing chamber (n = 30) and ensures valving if the dilution stage is completed (n = 15). Accuracy and precision of the automated serial dilution are verified by on-disk generation of qPCR standard curve dilutions and compared with manually generated reference dilutions. In a first step, the 5-log-stages standard curves are evaluated in a commercial qPCR thermocycler revealing a linearity of R² ≥ 99.92 % for the proposed LabDisk method vs. R² ≥ 99.67 % in manual reference dilutions. In a second step, the disk automated serial dilution is combined with on-disk qPCR thermocycling and readout, both inside a LabDisk Player. A 4-log-stages linearity of R² ≥ 99.81 % and a sensitivity of one leukemia associated ETV6-RUNX1 mutant DNA copy in a background of 100,000 wild-type DNA copies is achieved. K. Tröndle, F. Koch, G. Finkenzeller, G. B. Stark, R. Zengerle, P. Koltay, S. ZimmermannBioprinting of high cell density constructs leads to controlled lumen formation with self‐assembly of endothelial cells 2019 Journal of Tissue Engineering and Regenerative Medicine , volume : 13, issue : 10, pages : 1883 - 1895» show abstract « hide abstract Abstract Active nutrient supply and waste product removal are key requirements for the fabrication of long term viable and functional tissue constructs of considerable size. This work aims to contribute to the fabrication of artificial perfusable networks with a bioprinting process, based on drop‐on‐demand (DoD) printing of primary endothelial cell (EC) suspension bioink (25 · 106 ± 3 · 106 cells/ml). The process results in prescribed lumen between two hydrogel layers, allowing its integration in common layering based bioprinting processes. Low volume bioink droplets (appr. 10 nl) as building blocks, were deposited between two fibrin or collagen I layers to realize shapeable, cell‐rich aggregates. Unattainable with manual positioning, DoD printing allowed precise fabrication of various designs, such as spheroidal‐, line‐shaped and Y‐branch cellular structures, with a mean lateral extension of 285 ± 81 μm. For basic characterization, the cell suspension building blocks were systematically compared to preformed spheroids of the same cell type, passage and number. Post printing investigations of initially loose cell arrangements showed self‐assembly and formation of central lumen with a mean cross‐sectional area of Ølumen = 6400 μm2 at day 3, lined by a single layer of CD31 positive ECs, as evaluated by confocal microscopy. Originating from this main lumen smaller, undirected side‐branches (Øbranches = 740 μm2) were formed by sprouting cells, inducing a first step towards a simplistic hierarchically organized network. These lumen could prospectively help for tissue construct perfusion in vitro or, potentially, as niche for angiogenesis of host vascularization in implants. M. Schulz, F. von Stetten, R. Zengerle, N. PaustCentrifugal Step Emulsification: How Buoyancy Enables High Generation Rates of Monodisperse Droplets 2019 Langmuir : the ACS Journal of Surfaces and Colloids , volume : 35, issue : 30, pages : 9809 - 9815» show abstract « hide abstract Abstract We demonstrate that buoyancy in centrifugal step emulsification enables substantially higher generation rates of monodisperse droplets compared to pressure driven set-ups. Step emulsification in general can produce droplets in comparatively simple systems (only one moving liquid) with a low CV of <5% in droplet diameter and with a minimum dead volume. If operated below a critical capillary number, the droplet diameter is defined by geometry and surface forces only. Above that critical capillary number, however, jetting occurs, leading to an increased droplet diameter and CV. Consequently, generation rates of monodisperse droplets are limited in pressure-driven systems. In this paper, we show that centrifugal step emulsification can overcome this limitation by applying sufficient buoyancy to the system. The buoyancy, induced by the centrifugal field and a density difference of the continuous and disperse phase, supports droplet necking by pulling the forming droplet away from the nozzle. The influence of buoyancy is studied using specific microfluidic designs that allow for supplying different buoyancies to the same droplet generation rates. For a droplet diameter of 100 μm, droplet generation at rates above 2.8k droplets per second and nozzle were reached, which is an increase of more than a factor of 8 in comparison to pressure-driven systems. M. Wehrle, F. Koch, S. Zimmermann, P. Koltay, R. Zengerle, G. B. Stark, S. Strassburg, G. FinkenzellerExamination of Hydrogels and Mesenchymal Stem Cell Sources for Bioprinting of Artificial Osteogenic Tissues 2019 Cellular and Molecular Bioengineering , pages : 1 - 15» show abstract « hide abstract Abstract Mesenchymal stem cells (MSCs) represent a very important cell source in the field of regenerative medicine and for bone and cartilage tissue engineering applications. Three-dimensional (3D) bioprinting has the potential to improve the classical tissue engineering concept as this technique allows the printing of cells with high spatial control of cell allocation within a 3D construct. In this study, we systematically compared different hydrogel blends for 3D bioprinting of MSCs by testing their cytocompatibility, ability to support osteogenic differentiation and their mechanical properties. In addition, we compared four different MSC populations isolated from different human tissues for their osteogenic differentiation capacity in combination with different hydrogels. The aim of this study was to identify the best MSC source and the most suitable hydrogel blend for extrusion-based bioprinting of 3D large-scaled osteogenic constructs. D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. PaustFlow control for lateral flow strips with centrifugal microfluidics 2019 Lab Chip , pages : 2718 - 2727» show abstract « hide abstract Abstract Lateral flow strips (LFSs) are widely used for clinical diagnostics. The restricted flow control of the current designs is one challenge to the development of quantitative and highly sensitive LFSs. Here, we present a flow control for LFSs using centrifugal microfluidics. In contrast to previously presented implementations of lateral flow membranes into centrifugal microfluidic cartridges, we direct the flow radially outwards through the membrane. We control the flow using only the centrifugal force, thus it is independent of membrane wetting properties and permeability. The flow rate can be decreased and increased, enabling control of incubation times for a wide variety of samples. We deduced a formula as a guideline for the integration of chromatographic membranes into centrifugal microfluidic disks to ensure that all the sample liquid flows through the membrane, hence safely avoiding bypass flow around the membrane. We verified the calculated operation conditions using different membranes, different flow rates, and different sample viscosities. M. Bühler, P. Holzapfel, D. McLaughlin, S. ThieleFrom catalyst coated membranes to porous transport electrode based configurations in PEM water electrolyzers 2019 J Electrochem Soc , volume : 166, page : F1070» show abstract « hide abstract Abstract So far the superior cell polarization behavior of membrane electrode assemblies (MEAs) using catalyst coated membranes (CCMs) as compared to those using porous transport electrodes (PTEs) was a paradigm in proton exchange membrane water electrolyzers (PEMWEs). However, this paradigm was so far neither systematically investigated nor understood. In this study, we investigate the changes in PEMWE polarization behavior upon gradually changing the MEA from a full CCM toward a full PTE-type configuration. We explain all observed findings based on the idea for a structural model of discontinuous catalyst layers. Our results show, that for current densities above 750 mA cm−2, PTE-based MEAs can result in a better polarization behavior than CCMs. Therefore, the prevailing paradigm was disproved. CCMs showed better kinetics, while PTE-type configurations performed more reproducible than CCMs despite rougher surfaces. Due to the trend of a stabilizing HFR-free cell voltage, an improved mass transport behavior of the PTE-type configurations at high current densities is assumed. Within the error-tolerance, no clear differences between PTE and CCM-based configurations in ohmic resistance could be determined. We conclude that PTE-based configurations for PEMWE, as alternatives to standard CCM-configurations, could be highly important for future manufacturing techniques depending on the application's needs. F. Hegge, J. Sharman, R. Moroni, S. Thiele, R. Zengerle, M. Breitwieser, S. VierrathImpact of Carbon Support Corrosion on Performance Losses in Polymer Electrolyte Membrane Fuel Cells 2019 J Electrochem Soc , volume : 166, pages : F956 - F962» show abstract « hide abstract Abstract Corrosion of the carbon support leads to a severe decay in the performance of PEM fuel cells, mainly due to an increase in the oxygen transport resistance. To investigate the effect of degradation on oxygen transport, we cycled MEAs between 1−1.5 V and analyzed the electrode structure with FIB-SEM tomography at various ageing states. The tomography results show that the electrode structure changes over 1000 cycles in terms of thickness (7.8 to 6.5 μm), porosity (44 to 38%) and diffusivity (9 to 8 105 m2s−1). Limiting current measurements in the wet (hydrogen/air) and dry state (hydrogen pumping) allowed the pressure dependent and pressure independent mass transport resistances to be distinguished and to quantify the impact of product water. The pressure independent resistance increased from 24 to 41 sm−1. Considering the marginal contribution of the catalyst pore space resistance (3 to 4 sm−1) it is concluded that the largest portion of the increase (50%) is caused by an increased local mass transport resistance. This is due to a decrease of the electrode roughness factor (282 to 169). The limiting current under wet conditions shows that another 44% could stem from a change in the wetting behavior, while 6% remains unexplained. M. Solihul Mu’min, T. Böhm, R. Moroni, R. Zengerle, S. Thiele, S. Vierrath, M. BreitwieserLocal hydration in ionomer composite membranes determined with confocal Raman microscopy 2019 Journal of Membrane Science , volume : 585, pages : 126 - 135» show abstract « hide abstract Abstract Water management in electrochemical energy applications like fuel cells has a crucial impact on performance, in particular on the ionic conduction of ionomer membranes. To strengthen the understanding of water management in such devices, we report a novel method for non-destructive measurements of the hydration of composite membranes based on confocal Raman microscopy. Composite membranes were produced by spray-coating of Nafion into a mesh of electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyvinylpyrrolidone (PVDF-HFP/PVP) blend nanofibers. Hydration levels of several pure nanofiber meshes and nanofiber/Nafion composites were evaluated by linear least squares fitting of reference Raman spectra to hyperspectral images. We found that spectral contribution of water to nanofiber spectra depends on the PVDF-HFP/PVP ratio and is independent from fiber diameter. Further, we were able to reliably determine nanofiber polymer composition of single fibers based on Raman spectroscopy. Raman imaging of composite membranes was performed at ambient air and fully hydrated conditions to study the local hydration in PVDF-HFP/PVP/Nafion composites as well as in a Nafion XL membrane. 2D through-plane mappings revealed that the nanofiber hydration positively correlated with PVP content. In the Nafion XL membrane, the polytetrafluoroethylene-based reinforcement was verified as a hydrophobic layer sandwiched between Nafion ionomer, which showed a more than 10% reduced hydration compared to the outer Nafion layers. These results motivate the use of confocal Raman microscopy as a novel method to investigate the local water distribution in ionomer composite membranes that are widely used in electrochemical energy conversion. U. Karakus, T. Thamamongood, K. Ciminski, W. Ran, S. C. Günther, M. O. Pohl, D. Eletto, C. Jeney, D. Hoffmann, S. Reiche, J. Schinköthe, R. Ulrich, J. Wiener, M. G. B. Hayes, M. W. Chang, A. Hunziker, E. Yángüez, T. Aydillo, F. Krammer, J. Oderbolz, M. Meier, A. Oxenius, A. Halenius, G. Zimmer, C. Benner, B. G. Hale, A. García-Sastre, M. Beer, M. Schwemmle, S. StertzMHC class II proteins mediate cross-species entry of bat influenza viruses 2019 Nature , volume : 567, pages : 109 - 112» show abstract « hide abstract Abstract Zoonotic influenza A viruses of avian origin can cause severe disease in individuals, or even global pandemics, and thus pose a threat to human populations. Waterfowl and shorebirds are believed to be the reservoir for all influenza A viruses, but this has recently been challenged by the identification of novel influenza A viruses in bats1,2. The major bat influenza A virus envelope glycoprotein, haemagglutinin, does not bind the canonical influenza A virus receptor, sialic acid or any other glycan1,3,4, despite its high sequence and structural homology with conventional haemagglutinins. This functionally uncharacterized plasticity of the bat influenza A virus haemagglutinin means the tropism and zoonotic potential of these viruses has not been fully determined. Here we show, using transcriptomic profiling of susceptible versus non-susceptible cells in combination with genome-wide CRISPR–Cas9 screening, that the major histocompatibility complex class II (MHC-II) human leukocyte antigen DR isotype (HLA-DR) is an essential entry determinant for bat influenza A viruses. Genetic ablation of the HLA-DR α-chain rendered cells resistant to infection by bat influenza A virus, whereas ectopic expression of the HLA-DR complex in non-susceptible cells conferred susceptibility. Expression of MHC-II from different bat species, pigs, mice or chickens also conferred susceptibility to infection. Notably, the infection of mice with bat influenza A virus resulted in robust virus replication in the upper respiratory tract, whereas mice deficient for MHC-II were resistant. Collectively, our data identify MHC-II as a crucial entry mediator for bat influenza A viruses in multiple species, which permits a broad vertebrate tropism. M. Bühler, P. Holzapfel, F. Hegge, M. Bierling, S. Vierrath, S. ThieleOptimization of porous transport electrodes for PEM water electrolysis 2019 J Mater Chem A , volume : 165, page : F305» show abstract « hide abstract Abstract In this study we investigate the potential of porous transport electrode (PTE) based membrane electrode assemblies (MEAs) for proton exchange membrane water electrolysis. The focus is on the overpotential determining anodic PTE for the oxygen evolution reaction. The influences of catalyst loading, ionomer content and porous titanium substrate on the polarization behavior are analyzed. The comparison of a porous fiber-sintered substrate with a powder-sintered substrate shows no significant differences in the kinetic and mass transport regions. Ohmic losses, however, are lower for fiber PTEs above a catalyst loading of 1.0 mgIrO2 cm−2. Variations of the Nafion content in the catalyst layer reveal changes of mass transport and ohmic losses and have an influence on the reproducibility. Varying the noble metal loading and therefore the thickness of the applied catalyst layer influences the kinetic region and ohmic resistance of the MEAs. The best compromise between reproducibility and performance is found for a loading of 1.4 mgIrO2 cm−2 and 9 wt% Nafion. The stable operation of the aforementioned PTE is shown in a 200 h durability test at 2 A cm−2. J. F. Cahill, J. Riba, V. KerteszRapid, Untargeted Chemical Profiling of Single Cells in Their Native Environment 2019 Anal Chem , volume : 91, pages : 6118 - 6126» show abstract « hide abstract Abstract We report a method that enables untargeted,
high throughput, and quantitative mass spectrometric analysis
of single cells from cell suspension without needing additional
sample preparation procedures (e.g., molecular tagging)
through the combination of single-cell printer technology and
liquid vortex capture−mass spectrometry (SCP-LVC-MS). The
operating principle behind the SCP-LVC-MS technology is
single cell isolation via small droplet piezoelectric ejection
followed by capture of the droplet into an LVC-MS sampling
probe. Once exposed to an appropriate solvent, the cell is lysed,
extracted, and analyzed by MS. The SCP-LVC-MS approach
was validated by measuring the lipid composition of microalgae,
Chlamydomonas reinhardtii (ChRe) and Euglena gracilis (EuGr),
and HeLa cells in their native growth media. Numerous diacylglyceryltrimethylhomo-Ser (DGTS), phosphatidylcholine (PC),
monogalactosyldiacylglycerol (MGDG), and digalactosyldiacylglycerol (DGDG) lipids were observed in single cells.
Continuous solvent flow ensures that cells are analyzed rapidly, and no signal carryover between cells is observed. ChRe
and EuGr microalgae mixed together in the same solution were differentiated cell-by-cell in real-time based on differences
between levels of diacylglyceryltrimethylhomo-Ser (DGTS) and phosphatidylcholine (PC) lipids measured in each cell. Several
DGTS lipids present in ChRe were quantified with single-cell resolution by normalizing to a DGTS(32:0) internal standard
added to the LVC probe solvent during analysis. Quantitative peak areas were validated by comparing to bulk lipid extracts.
Lastly, peak area distributions comprised of hundreds of cells were compared for ChRe after 5 days of nitrogen-limited and
normal growth conditions, which show clear differences and the ability to resolve cellular population differences with single-cell
resolution. T. Boehm, R. Moroni, M. Breitwieser, S. Thiele, S. VierrathSpatially Resolved Quantification of Ionomer Degradation in Fuel Cells by Confocal Raman Microscopy 2019 J Electrochem Soc , volume : 166, issue : 7, pages : F3044 - F3051» show abstract « hide abstract Abstract Ionomer membranes are crucial components of many electrochemical devices. In this work, confocal Raman microscopy is employed to characterize Nafion ionomers quantitatively in pristine status and after usage as a proton exchange membrane in a fuel cell. Confocal Raman microscopy allows non-destructive thickness and equivalent weight measurements of Nafion with a 95% confidence interval of ±13 g mol−1 at an equivalent weight of 1000 g mol−1, which is significantly more accurate than previously reported methods. Characterization can be performed at a spatial resolution better than 2 μm, providing insights into local membrane degradation after fuel cell operation. Membrane thinning to less than 40% of the initial thickness of Nafion NR-211 occurs after a 100 h open circuit voltage hold, accompanied by an anisotropic increase of the equivalent weight from 1035 g mol−1 to an average of 1200 g mol−1. Most pronounced increases are found close to the anode. Further, the characterization of a Nafion XL membrane shows that its microporous reinforcement is represented as increased equivalent weight with local heterogeneities within the membrane. These results show that confocal Raman microscopy is a valuable tool to investigate ionomers that are used as ion exchange membranes in electrochemical devices. J.P. Hays, K. Mitsakakis, S. Luz, A. van Belkum, K. Becker, A. van den Brue, S. Harbarth, J. H. Rex, G. Skov Simonsen, G. Werner, V. Di Gregori, G. Lüdke, T. van Staa, J. Moran-Gilad, T. T. Bachmann, on behalf of the JPIAMR AMR-RDTThe successful uptake and sustainability of rapid infectious disease
and antimicrobial resistance point-of-care testing requires a complex
‘mix-and-match’ implementation package 2019 Eur J Clin Microbiol , volume : 38, pages : 1015 - 1022» show abstract « hide abstract Abstract The emergence and spread of antimicrobial resistance is one of the major global issues currently threatening the health and wealth
of nations, with effective guidelines and intervention strategies urgently required. Such guidelines and interventions should
ideally be targeted at individuals, communities, and nations, requiring international coordination for maximum effect. In this
respect, the European Joint Programming Initiative on Antimicrobial Resistance Transnational Working Group ‘Antimicrobial
Resistance - Rapid Diagnostic Tests’ (JPIAMR AMR-RDT) is proposing to consider a ‘mix-and-match’ package for the implementation
of point-of-care testing (PoCT), which is described in this publication. The working group was established with the
remit of identifying barriers and solutions to the development and implementation of rapid infectious disease PoCT for combatting
the global spread of antimicrobial resistance. It constitutes a multi-sectoral collaboration between medical, technological, and
industrial opinion leaders involved in in vitro diagnostics development, medical microbiology, and clinical infectious diseases.
The mix-and-match implementation package is designed to encourage the implementation of rapid infectious disease and antimicrobial
resistance PoCT in transnational medical environments for use in the fight against increasing antimicrobial resistance. back to the year overview E. Kipf, S. Sané, D. Morse, T. Messinger, R. Zengerle, S. KerzenmacherAn air-breathing enzymatic cathode with extended lifetime by continuous laccase supply 2018 Bioresource Technol , volume : 264, pages : 306 - 310» show abstract « hide abstract Abstract We present a novel concept of an air-breathing enzymatic biofuel cell cathode combined with continuous supply
of unpurified laccase-containing supernatant of the white-rot fungus Trametes versicolor for extended lifetime.
The air-breathing cathode design obviates the need for energy-intensive active aeration. In a corresponding longterm
experiment at a constant current density of 50 μA cm−2, we demonstrated an increased lifetime of 33 days
(cathode potential above 0.430 V vs. SCE), independent of enzyme degradation. The obtained data suggest that
theoretically a longer lifetime is feasible. However, further engineering efforts are required to prevent clogging
and fouling of the supply tubes. These results represent an important step towards the realization of enzymatic
biofuel cell cathodes with extended lifetime and enhanced performance. B. Gerdes, M. Breitwieser, T. Kaltenbach, M. Jehle, J. Wilde, R. Zengerle, P. Koltay, L. RieggerAnalysis of the metallic structure of microspheres produced by printing of aluminum alloys from the liquid melt 2018 Mater Res Express , volume : 6, page : 036514» show abstract « hide abstract Abstract This work presents an analysis of the metallic structure of microspheres produced by drop-on-demand printing of the aluminum alloy AlSi12 directly printed from the liquid melt via StarJet technology. AlSi alloys are commonly used in casting processes, but microdroplets from these materials could potentially be used for additive manufacturing of metal and composite parts. Recently, several printing technologies were presented that enable the drop-on-demand printing of Al-alloy microdroplets. However, the material distribution and metallic structure inside of printed droplets is expected to be significantly different from the bulk material properties, and hardly any data on the microscopic structure of small droplets that have undergone rapid solidification has been published so far. Therefore, a microscopic in-depth study of microdroplets printed directly from the metal melt has been carried out: By the means of energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and optical microscopy the material properties as well as the droplet morphology are investigated for the first time. The analysis demonstrates that the Al alloy droplets printed via StarJet technology exhibit almost no oxidation during the printing process and can therefore potentially be used for additive manufacturing of metal parts. Moreover, the metallurgical structure inside the droplets is analyzed. It exhibits significant difference to the bulk material in terms of the average secondary dendrite arm spacing. J. Streeck, C. Hank, M. Neuner, L. Gil-Carrera, M. Kokko, S. Pauliuk, A. Schaadt, S. Kerzenmacher, R. J. WhiteBio-electrochemical conversion of industrial wastewater-COD combined with downstream methanol synthesis – an economic and life cycle assessment 2018 Green Chem , volume : 20, pages : 2742 - 2762» show abstract « hide abstract Abstract Herein, a techno-economic and environmental performance evaluation (i.e. Life Cycle Assessment (LCA))
of a 45 kW Microbial Electrolysis Cell (MEC) system is presented in the context of industrial wastewater
remediation. This system produces H2 and CO2 – suitable for downstream CH3OH synthesis – based on
the bio-electrochemical conversion of chemical industry wastewater with an organic content of 3.9
g(COD) L−1. A cost–benefit analysis indicates that the MEC system hardware costs, share of CO2 captured
from the MEC and MEC operating current density (i.e. 1.0 mA cm−2) are crucial parameters influencing
the total cost and represent areas for potential cost reductions. It was established based on the present
study that MEC system operation with renewable electricity leads to H2 production costs of 4–5.7€
kg(H2)
−1 (comparable to H2O electrolysis) and CH3OH production costs of 900€ t(CH3OH)
−1. At the current
CH3OH market prices, however, the production is currently not profitable. In turn, the cost-efficient construction
of the MEC system and the use of less expensive materials could lead to improved CH3OH production
economics based on this route. Our results indicate that the use of low-cost materials has
greater potential with regard to cost reduction compared to reducing the internal resistance and polarization
losses via the use of expensive high-performance materials in MEC construction. A complementary
LCA of the proposed system, based on a “cradle-to-gate” definition, indicates that waste-based is superior
to fossil-based CH3OH production with respect to global warming potential and cumulated fossil energy
demand, provided the system is operated with 100% renewable electricity and CO2 sourced only from the
MEC. However, with regard to the impact categories Metal Depletion and Freshwater Eutrophication
Potential, the system was found to perform less satisfactorily (i.e. in comparison with fossil-based CH3OH
production). K. Mitsakakis, W.E. Kaman, G. Elshout, M. Specht, J.P. HaysChallenges in identifying antibiotic resistance targets for point-of-care diagnostics in general practice 2018 Future Microbiol , volume : 13, issue : 10, pages : 1157 - 1164» show abstract « hide abstract Abstract General practitioners stand at the front line of healthcare provision and have a pivotal role in the fight against increasing antibiotic resistance. In this respect, targeted antibiotic prescribing by general practitioners would help reduce the unnecessary use of antibiotics, leading to reduced treatment failures, fewer side-effects for patients and a reduction in the (global) spread of antibiotic resistances. Current ‘gold standard’ antibiotic resistance detection strategies tend to be slow, taking up to 48 h to obtain a result, although the implementation of point-of-care testing by general practitioners could help achieve the goal of targeted antibiotic prescribing practices. However, deciding on which antibiotic resistances to include in a point-of-care diagnostic is not a trivial task, as outlined in this publication. S. H. Moosavi, M. Kroener, M. Frei, F. Frick, S. Kerzenmacher, P. WoiasDevelopment of a TEM Compatible Nanowire Characterization Platform With Self-forming Contacts 2018 Ieee T Semiconduct M , volume : 31, issue : 1, pages : 1 - 10» show abstract « hide abstract Abstract A nanowire characterization platform is designed and fabricated in MEMS-technology for the thermoelectric and structural characterization of single nanowires. The latter is achieved by making the chip compatible to TEM holder, by restricting its thickness to less than 160μm and its diagonal dimensions to less than 3mm. Two different fabrication technologies are presented for the realization of such platform, based on a design reproducing the functional requirements. Our first fabrication technique is based on ICP etching, using (100)-silicon wafers, and a subsequent rear grinding. However, as the design includes a vertical wall trench structures, ICP etching of such deep recesses is time-consuming and expensive. Therefore, a second fabrication process is developed, making use of wet-etched (110)-silicon. With these substrates a challenge arises from the intersection of inclined {111} facets. To solve this natural limitation, we introduce a novel fabrication process. Our technique relies on damaging the intersecting {111} planes, to make them etchable again and to produce deeper trenches with vertical walls in a wet-chemical etching process. Additionally, the electrical contacts at the platform are made from porous metal to increase the surface-to-volume ratio, to increase the possibility of a spontaneous electrical contact between the electrodes and nanowires. C.H. Tsai, X. Wu, D.H. Kuan, S. Zimmermann, R. Zengerle, P. KoltayDigital hydraulic drive for microfluidics and miniaturized cell culture devices based on shape memory alloy actuators 2018 J Micromech Microeng , volume : 28, page : 084001» show abstract « hide abstract Abstract In order to culture and analyze individual living cells, microfluidic cell culture and manipulation of cells becomes an increasingly important topic. Such microfluidic systems allow for exploring the phenotypic differences between thousands of genetically identical cells or pharmacological tests in parallel, which is impossible to achieve by traditional macroscopic cell culture methods. Therefore, plenty of microfluidic devices have been developed for cell biological studies like cell culture, cell sorting, and cell lysis in the past. However, these devices are still limited by the external pressure sources which most of the time are large in size and have to be connected by fluidic tubing leading to complex and delicate systems. In order to provide a miniaturized, more robust actuation system a novel, compact and low power consumption Digital Hydraulic Drive (DHD) has been developed that is intended for use in portable and automated systems for microfluidic applications. The DHD consists of a shape memory alloy (SMA) actuator and a pneumatic cylinder. The switching time of the digital modes (pressure ON vs. OFF) can be adjusted from 1 second to minutes. Thus, the DHDs might have many applications for driving microfluidic devices. In this work different implementations of DHDs are presented and their performance is characterized by experiments. In particular, it will be shown that DHDs can be used for microfluidic large-scale integration (mLSI) valve control (256 valves in parallel) as well as potentially for droplet-based microfluidic systems. As further application example high-throughput mixing of cell cultures (96 wells in parallel) are demonstrated employing the DHD and a so called "functional lid" (FL) approach, to enable a miniaturized microbioreactor in a regular 96-well micro well plate. B. Gerdes, R. Zengerle, P. Koltay, L. RieggerDirect printing of miniscule aluminum alloy droplets and 3D structures by StarJet technology 2018 J Micromech Microeng , volume : 28, page : 074003» show abstract « hide abstract Abstract Drop-on demand printing of molten metal droplets could be used for prototyping of 3D objects as promising alternative to laser melting technologies. However, up to date only few printheads were investigated for this purpose using only a limited range of materials. The pneumatically actuated StarJet technology presented previously enables the direct and non-contact printing of molten metal microdroplets from metal melts at high temperatures. Printheads according to the StarJet technology utilize nozzle chips featuring a star-shaped orifice geometry that leads to a formation of the droplets inside the nozzle with high precision. In this paper we present a novel StarJet printhead for printing aluminum alloys featuring a hybrid design with a ceramic reservoir for the molten metal and an outer shell fabricated from stainless steel. The micro machined nozzle chip is made from silicon carbide (SiC). This printhead can be operated at up to 950 °C and is capable of printing high melting metals like aluminum (Al) alloys in standard laboratory conditions. In this work, an aluminum-silicon alloy that features 12 % silicon (AlSi12) is printed. The printhead, the nozzle and the peripheral actuation system have been optimized for stable generation of AlSi12 droplets with high monodispersity, low angular deviation and miniaturized droplet diameters. As main result, a stable drop-on-demand printing of droplets exhibiting diameters of ddroplet = 702 µm +/- 1 % was demonstrated at 5 Hz with a low angular deviation of 0.3°, when a nozzle chip with 500 µm orifice diameter was used. Further, AlSi12 droplets featuring ddroplet = 176 µm ± 7 % were printed when using a nozzle chip with an orifice diameter of 130 µm. Moreover, we present directly printed objects from molten aluminum alloy droplets such as high aspect ratio, free-standing walls (aspect ratio 12:1) and directly printed, flexible springs to demonstrate the principle of 3D printing with molten metal droplets. C. Van Pham, B. Britton, T. Böhm, S. Holdcroft, S. ThieleDoped, Defect-Enriched Carbon Nanotubes as an
Efficient Oxygen Reduction Catalyst for Anion
Exchange Membrane Fuel Cells 2018 Adv Mater Interfaces , page : 1800184» show abstract « hide abstract Abstract Bond polarization of doped atoms and carbon and lattice defects are con-
sidered important aspects in the catalytic mechanisms of oxygen reduction
reaction (ORR) on heteroatom-doped carbon catalysts. Previous work on
metal-free catalysts has focused either on bond polarization or lattice defects.
Here multi-heteroatom doped defect-enriched carbon nanotubes (MH-DCNTs)
that combine both effects to enhance ORR activity are designed. Lattice
defects in MH-DCNTs are enriched by unzipping and length-shortening of
carbon nanotubes, and also by creating carbon vacancies via decomposition of
doped F atoms. Electrochemical analysis using rotating disc electrode voltam-
metry shows that the ORR kinetic current density of MH-DCNT increases with
lattice-defect density, the latter of which is verified by Raman spectroscopy,
while the onset potential increases with annealing temperatures. An optimized
MH-DCNT ORR catalyst exhibits a half-wave potential of 0.81 V versus revers-
ible hydrogen electrode and limiting current density of 5.0 mA cm
−2
at an
electrode rotation speed of 1600 rpm in 0.1
M KOH. Further, it is demonstrated
that MH-DCNT, as a cathode catalyst layer in an anion exchange membrane
fuel cell (AEMFC), delivers a peak power density of 250 mW cm
−2
, which is
≈70% the performance of an AEMFC using a conventional Pt/C catalyst. M. Lehnert, E. Kipf, F. Schlenker, N. Borst, R. Zengerle, F. von StettenFluorescence signal-to-noise optimisation for real-time PCR using universal reporter oligonucleotides 2018 Anal Methods-uk » show abstract « hide abstract Abstract In this study we optimised the fluorescence signal generation of contact quenched universal reporter oligonucleotides. These are used as secondary probes in real-time Mediator Probe PCR to detect the sequence-specific cleavage of label-free primary mediator probes. Since the fluorescence signal generation of a universal reporter is not influenced by the target DNA sequence, optimisation of the fluorescence signal-to-noise ratio will improve the performance of all Mediator Probe PCRs that are based on this type of universal reporter. To determine the critical factors influencing signal-to-noise optimisation, we systematically analysed four parameters. These parameters were type of fluorophore, type of quencher molecule, intramolecular orientation of both residuals, and the number of quencher labels. In total, more than 30 different fluorogenic universal reporter structures were analysed, covering the whole fluorescence spectrum from green to crimson. From our results, we deduced a novel set of guidelines for signal-to-noise optimisation in the design of contact quenched, fluorogenic universal reporter oligonucleotides. We confirmed these guidelines in a different thermocycler, and by designing a second set of universal reporters, which were used for multiplex real-time PCR quantification of acute lymphoblastic leukaemia marker sequences. This optimised biplex Mediator Probe PCR showed an improved performance under clinical conditions, with a 10 times higher resolution regarding the limit of quantification. In addition to Mediator Probe PCR, these guidelines may also prove useful in signal-to-noise optimisation of other fluorescence-based assays where contact quenched oligonucleotides or secondary reporter molecules are used. B. Gerdes, M. Jehle, N. Lass, L. Riegger, A. Spribille, M. Linse, F. Clement, R. Zengerle, P. KoltayFront side metallization of silicon solar cells by direct printing of molten metal 2018 Solar Energy Materials and Solar Cells , volume : 180, pages : 83 - 90» show abstract « hide abstract Abstract In this work, a new approach for the front side metallization of silicon solar cells is presented. Molten solder
(Sn96Ag3Cu) is directly printed in a non-contact manner on solar cell precursors via StarJet technology. The
StarJet technology features a pneumatically driven, heatable printhead with a reservoir of molten metal and a
star-shaped silicon nozzle chip. Using this printhead, a jet of molten metal with 55 μm ± 5 μm diameter is
generated and used to apply busbars as well as contact fingers on prefabricated electroplated seed layers. After
deposition via StarJet, printed fingers have a minimum width of 70 μm and a mean aspect ratio of 0.94. The
printed metallization is evaluated optically and electrically. Aluminum back surface field silicon solar cells with
front side electroplated NiAg seed layers and StarJet metallization (busbars and fingers) show efficiencies of up
to 18.1% after degradation. Solder is about 30–40 times cheaper than silver and therefore may allow costefficient
solar cell metallization. The StarJet metallization on electroplated NiAg seed layers is fully functional
and requires no additional post-processing steps. Only 6 mg of Ag per cell are consumed for the seed layer. As a
proof-of-principle, a module is demonstrated, which consists of four solar cells that are metallized via StarJet. K. Kraiczek, G. Rozing, R. ZengerleG-Index: A New Metric to Describe Dynamic Refractive Index Effects in HPLC Absorbance Detection 2018 Talanta , volume : 187, pages : 200 - 206» show abstract « hide abstract Abstract High performance liquid chromatography (HPLC) with a solvent gradient and absorbance detection is one of the most widely used methods in analytical chemistry. The observed absorbance baseline is affected by the changes in the refractive index (RI) of the mobile phase. Near the limited of detection, this complicates peak quantitation. The general aspects of these RI-induced apparent absorbance effects are discussed. Two different detectors with fundamentally different optics and flow cell concepts, a variable-wavelength detector equipped with a conventional flow cell and a diode-array detector equipped with a liquid core waveguide flow cell, are compared with respect to their RI behavior. A simple method to separate static – partly unavoidable – RI effects from dynamic RI effects is presented. It is shown that the dynamic RI behavior of an absorbance detector can be well described using a single, relatively easy-to-determine metric called the G-index. The G-index is typically in the order of a few seconds and its sign depends on the optical flow cell concept. J. M. Stosch, A. Heumüller, C. Niemöller, S. Bleul, M. Rothenberg-Thurley, J. Riba, N. Renz, K. Szarc vel Szic, D. Pfeifer, M. Follo, H. L. Pahl, S. Zimmermann, J. Duyster, J. Wehrle, M. Lübbert, K. H. Metzeler, R. Claus, H. BeckerGene mutations and clonal architecture in myelodysplastic syndromes and changes upon progression to acute myeloid leukaemia and under treatment 2018 Brit J Haematol , volume : 182, pages : 830 - 842» show abstract « hide abstract Abstract Knowledge of the molecular and clonal characteristics in the myelodysplastic
syndromes (MDS) and during progression to acute myeloid leukaemia
(AML) is essential to understand the disease dynamics and optimize treatment.
Sequencing serial bone marrow samples of eight patients, we
observed that MDS featured a median of 3 mutations. Mutations in genes
involved in RNA-splicing or epigenetic regulation were most frequent, and
exclusively present in the major clone. Minor subclones were distinguishable
in three patients. As the MDS progressed, a median of one mutation
was gained, leading to clonal outgrowth. No AML developed genetically
independent of a pre-existing clone. The gained mutation mostly affected
genes encoding signalling proteins. Additional acquisition of genomic aberrations
frequently occurred. Upon treatment, emergence of new clones
could be observed. As confirmed by single-cell sequencing, multiple mutations
in identical genes in different clones were present within individual
patients. DNA-methylation profiling in patients without identification of
novel mutations in AML revealed methylation changes in individual genes.
In conclusion, our data complement previous observations on the mutational
and clonal characteristics in MDS and at progression. Moreover,
DNA-methylation changes may be associated with progression in single
patients. Redundancy of mutated genes in different clones suggests fertile
grounds promoting clonal selection or acquisition. C. Klose, P. Trinke, T. Böhm, B. Bensmann, S. Vierrath, R. Hanke-Rauschenbach, S. ThieleMembrane Interlayer with Pt Recombination Particles for Reduction of the Anodic Hydrogen Content in PEM Water Electrolysis 2018 J Electrochem Soc , volume : 165, pages : F1271 - F1277» show abstract « hide abstract Abstract Polymer electrolyte membrane (PEM) water electrolysis is a key technology for sustainable hydrogen based energy supply. Gaspermeation through the PEM leads to hydrogen in oxygen at the anode side posing a safety hazard and therefore restricting theoperation window of PEM water electrolysis, especially when operating under pressure. In this work the hydrogen in oxygen contentat the anode is significantly reduced when a recombination interlayer is integrated into the membrane electrode assemblies (MEAs)compared to reference MEAs without interlayer. The recombination interlayer with a platinum loading of 0.02 mg cm−2is sprayedbetween two membranes that are coated with anode and cathode catalysts on the outside. The permeating H2and O2forms waterat the recombination interlayer, leading to higher gas purity and resolving safety issues. In case of the MEAs with interlayer alsoa constant current hold at 1 A cm−2for 245 h revealed only a slight increase of the hydrogen in oxygen content (below 140·10−6vol.% h−1) whereas for the reference MEAs without interlayer a stronger increase was observed (above 1250·10−6vol.% h−1).Furthermore, the long-term experiments showed no increased degradation rates compared to the reference MEAs. S. Hin, M. Loskyll, V. Klein, M. Keller, O. Strohmeier, F. von Stetten, R. Zengerle, K. MitsakakisMembrane-based sample inlet for centrifugal microfluidic cartridges 2018 Microelectron Eng , volume : 187-188, pages : 78 - 83» show abstract « hide abstract Abstract Centrifugal microfluidics enables the rapid execution of complex blood sample analyses in a fully automated manner at the point of care. However, during blood sample addition, the cartridge is at rest and centrifugal forces are not present to allocate the sample in a controlled way. We present a versatile approach for the user-friendly, well-controlled and safe sample addition into a centrifugal microfluidic cartridge for use in serology. It features a commercial (plasma separation) membrane stacked into the inlet chamber of the cartridge. This combination of sample inlet and plasma separation in one structural unit brings the advantage of reducing footprint in highly integrated point-of-care testing. By using a pipette the user may add a blood sample (90 μL) to the membrane holding the liquid by capillary forces. Flowing across the membrane, cells separate from blood plasma. The blood plasma releases into the downstream structure upon centrifugation. The mean plasma recovery rate was 57.3 (± 4.7) % and mean plasma purity 99.5 (± 0.6) % from samples of varying hematocrit (36%–59%). Furthermore, the analyte C-reactive protein (CRP) did not significantly adsorb to the membrane. This was concluded, since CRP immunoassay results with plasma from spiked whole blood, obtained from membrane-based plasma separation and from plasma separation on a standard laboratory centrifuge, did not significantly differ. Thus, the suggested approach is promising for simultaneous application as sample inlet holding the sample by capillary forces and as a plasma separation module for centrifugal microfluidics. Potential future applications may include other sample matrices. The use with further blood transfer devices (capillary, directly from fingertip) seems possible, yet requiring further evaluation. M. Frei, J. Martin, S. Kindler, G. Cristiano, R. Zengerle, S. KerzenmacherPower supply for electronic contact lenses: Abiotic glucose fuel cells vs. Mg/air batteries 2018 J Power Sources , volume : 401, pages : 403 - 414» show abstract « hide abstract Abstract Electronic contact lenses are a promising platform for medical sensors. With these devices a variety of vital signs and medical parameters can be monitored noninvasively and without the risk of foreign body response. However, one current limitation of this technology is the need for an external power supply, resulting in bulky, multi component devices. In this paper, we for the first time investigate and compare the application of abiotic glucose fuel cells and Mg/air batteries as alternative power supply technologies for electronic contact lenses. While abiotic glucose fuel cells harvest energy from metabolites present in tear fluid, Mg/air batteries provide electricity by the oxidation of a sacrificial anode. Considering the space available on standard contact lenses, our results indicate that approx. 40 μW and 2 μW can be generated by Mg/air batteries and glucose fuel cells for a period of at least 24 h, respectively. However, coating galvanic cells with the commonly used contact lens material pHEMA, results in drastically reduced performance, presumably due to hindered mass transport. Nevertheless, even under those circumstances a Mg/air battery can still provide about 7 μW for 24 h, which would already be sufficient for many electronic contact lens applications. M. Frei, C. Köhler, L. Dietel, J. Martin, F. Wiedenmann, R. Zengerle, S. KerzenmacherPulsed electro-deposition of highly porous Pt-alloys for the use in methanol, formic acid, and glucose fuel cells 2018 Chemelectrochem , pages : 1013 - 1023» show abstract « hide abstract Abstract We demonstrate an electro-deposition process for the
fabrication of highly porous PtCu-alloy anodes. In the fabrication
process, Pt and different amounts of a second noble metal (Pd, Ru,
Au) are repeatedly co-deposited with Cu from an aqueous electrolyte,
followed by selective dealloying of Cu. This way, highly porous PtCu
alloys with roughness factors ranging from 400 to 4000 can be
obtained. In all cases both noble metal partners are present on the
electrode surface, whereas the majority of copper is likely buried
underneath. In addition, we can show that H-desorption and COstripping
yield substantially different roughness factors, even when
applied to PtCu anodes. Hence, when using or comparing results
from different stripping methods a calibration is required. Compared
to PtCu anodes, small additions of Ru (~3 at% Ru) lead to
significantly enhanced catalytic activity for the electro-oxidation of
formic acid and methanol, whereas Au-rich PtCu-Au alloys (~75 at%
Au) exhibit significantly improved electro-catalytic activity for glucose
oxidation. In some cases, large variations impede the identification
of significant differences in electro-catalytic activity. To reduce
process variability and to increase the specific surface area further
optimization of the fabrication process is required. Similarly, the
deposition of defined alloy compositions will require further
investigation since the composition of electrolyte and deposited alloy
do not directly correspond. L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von StettenSimplified real-time multiplex detection of loop-mediated isothermal amplification (LAMP) using novel mediator displacement probes with universal reporters 2018 Anal Chem , volume : 90, pages : 4741 - 4748» show abstract « hide abstract Abstract A variety of real-time detection techniques for LAMP based on the change in fluorescence intensity during DNA amplification enable simultaneous detection of multiple targets. However these techniques depend on fluorogenic probes containing target-specific sequences. That complicates the adaption to different targets leading to time-consuming assay optimization. Here, we present the first universal real-time detection technique for multiplex LAMP. The novel approach allows simple assay design and is easy to implement for various targets. The innovation features a mediator displacement probe and a universal reporter. During amplification of target DNA the mediator is displaced from the mediator displacement probe. Then it hybridizes to the reporter generating a fluorescence signal. The novel Mediator Displacement (MD) detection was validated against state-of-the-art molecular beacon (MB) detection by means of a HIV-1 RT-LAMP: MD surpassed MB detection by accelerated probe design (MD: 10 min, MB: 3-4 h), shorter times to positive (MD 4.1±0.1 min shorter than MB, n = 36), improved signal to noise fluorescence ratio (MD: 5.9±0.4, MB: 2.7±0.4; n = 15) and showed equally good or better analytical performance parameters. The usability of one universal mediator-reporter set in different multiplex assays was successfully demonstrated for a biplex RT-LAMP of HIV-1 & HTLV-1 and a biplex LAMP of Haemophilus ducreyi & Treponema pallidum, both showing good correlation between target concentration and time to positive. Due to its simple implementation it is suggested to extend the use of the universal mediator-reporter sets to the detection of various other diagnostic panels. J. Madjarov, A. Götze, R. Zengerle, S. KerzenmacherSimultaneous use of a crossflow filtration membrane as
microbial fuel cell anode – permeate flow leads to 4-fold
increased current densities 2018 Bioresource Technol , volume : 257, pages : 274 - 280» show abstract « hide abstract Abstract A new concept for the combination of membrane bioreactors and microbial fuel cells
is introduced, that aims at the production of electricity for reducing the overall energy
consumption of wastewater treatment. In contrast to previous approaches, the anode
is integrated as microfiltration membrane in sidestream crossflow configuration.
Using a stainless steel filtration membrane with G. sulfurreducens and an acetatebased
synthetic medium, up to 4-fold higher current densities are achieved. In a
standard setup without filtration, a membrane of filter grade 1 μm shows current
densities of 5.8 A m-2 ± 0.5 A m-2 compared to >11 A m-2 when it is used
simultaneously as membrane filter. With smaller pore sizes of filter grade 0.5 μm 4.4
A m-2 ± 0.5 A m-2 in a standard setup and >15 A m-2 in a filtration setup are achieved.
The permeate flow was identified as the main parameter leading to increased current
densities. E. Kipf, J. Erben, R. Zengerle, J. Gescher, S. KerzenmacherSystematic investigation of anode materials for microbial fuel
cells with the model organism G. sulfurreducens 2018 Bioresource Technology Reports , volume : 2, pages : 29 - 37» show abstract « hide abstract Abstract Different carbon and metal-based anode materials for microbial fuel cells were
systematically investigated with a pure culture of the model organism G.
sulfurreducens. The highest limiting current density of 756 ± 15 μA cm-2 at -0.253 ±
0.037 V vs. SCE was achieved with graphite foil using a step-wise galvanostatic
technique. But also the application of completely different anode materials such as
activated carbon cloth, stainless steel and graphite felt led to similar high limiting
current densities, suggesting that G. sulfurreducens is able to use a large range of
substantially different anode materials as external electron acceptor. Additionally, we
could show that a step-wise galvanostatic technique to record polarization curves yields similar current densities as potentiostatic control at -0.400 V vs. SCE with the
investigated carbon-based materials. In case of stainless steel these techniques yield
slightly different results, presumably due to an effect related to the material’s surface
properties. S. Hin, N. Paust, M. Keller, M. Rombach, O. Strohmeier, R. Zengerle, K. MitsakakisTemperature change rate actuated bubble mixing
for homogeneous rehydration of dry pre-stored
reagents in centrifugal microfluidics 2018 Lab Chip , volume : 18, pages : 362 - 370» show abstract « hide abstract Abstract In centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided.
These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here
we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs
heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of
mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter
with respect to pressure changes. Fast temperature increase causes rapid pressure increase in downstream
structures pushing the liquid from downstream channels into the mixing chamber. As air further penetrates
into the mixing chamber, bubbles form, ascend due to buoyancy and mix the liquid. Slow temperature/
pressure changes equilibrate through the high fluidic resistance air vent enabling sequential heating/cooling
cycles to repeat the mixing process. After mixing, a complete transfer of the reaction volume into the
downstream fluidic structure is possible by a rapid cooling step triggering TCR actuated valving. The new
mixing concept is applied to rehydrate reagents for loop-mediated isothermal amplification (LAMP). After
mixing, the reaction mix is aliquoted into several reaction chambers for geometric multiplexing. As a measure
for mixing efficiency, the mean coefficient of variation (C
——
V, n = 4 LabDisks) of the time to positivity (tp)
of the LAMP reactions (n = 11 replicates per LabDisk) is taken. The C
——
V of the tp is reduced from 18.5%
(when using standard shake mode mixing) to 3.3% (when applying TCR actuated bubble mixing). The bubble
mixer has been implemented in a monolithic fashion without the need for any additional actuation besides
rotation and temperature control, which are needed anyhow for the assay workflow. F. Hegge, R. Moroni, P. Trinke, B. Bensmann, R. Hanke-Rauschenbach, S. Thiele, S. VierrathThree-dimensional microstructure analysis of a polymer electrolyte membrane water electrolyzer anode 2018 J Power Sources , volume : 393, pages : 62 - 66» show abstract « hide abstract Abstract The anode catalyst layer of a PEM water electrolyzer is reconstructed using a combination of FIB-SEM tomography and ionomer modeling. The pore space is infiltrated with silicone, enabling good discrimination between pores and IrRuOx catalyst material, while the ionomer cannot be imaged. The reconstructed volume of 29 μm × 24 μm x 7 μm contains catalyst particles with a median size of 0.5 μm and has a porosity of 55%. By modeling different ionomer contents inside the pore space, the impact on microstructural and transport parameters is investigated. At an ionomer content of 40–50% of the pore volume, all transport parameters are in a reasonable range, confirming experimental results from literature. At an ionomer content of 48% the catalyst layer has a porosity of 29%, a median pore size of 0.94 μm, a permeability of the pore space of and a mean ionomer film thickness of . The tortuosities of the ionomer and the pore space are calculated to 3.5 and 6.7 at the corresponding phase fractions of 26% and 29% respectively. The electrochemically active surface area estimated from the tomography () is considerably lower than literature values, indicating a roughness below FIB-SEM resolution. N. P. Kocatürk-Schumacher, J. Madjarov, P. Viwatthanasittiphong, S. KerzenmacherToward an Energy Efficient Wastewater Treatment: Combining a Microbial Fuel Cell/Electrolysis Cell Anode With an Anaerobic Membrane Bioreactor 2018 Frontiers in Energy Research , volume : 6, page : 95» show abstract « hide abstract Abstract Recently, it has been shown that combining a bioelectrochemical system (BES) with an
anaerobic membrane bioreactor (AnMBR) to produce electricity can reduce the overall
energy consumption of wastewater treatment. In this study, we tested the recently
proposed concept that integrates a microbial anode into an AnMBR, under application
relevant conditions, for the treatment of synthetic brewery wastewater. We developed
two system configurations: a filtering anode with stainless steel filter plate; and a hybrid
anode, in which a polymeric membrane is combined with stainless steel mesh. As fouling
is problematic in AnMBRs, we investigated the effect of two fouling mitigation methods,
namely electrochemical cleaning and application of a turbulence promotor, on the
permeate fluxes and current densities.We also investigated the effect of cathode (counter
electrode) position on the permeate fluxes and current densities in filtering and hybrid
anode. Our results revealed that permeate fluxes were influenced by the membrane pore
size; and dropped below 5 L m−2 hr−1 on day 3 with filter grade 0.5μm; whereas similar
values of permeate flux were observed after 5 days of operation with the membrane
with filter grade 0.1μm. COD removal across the membrane reached up to 644mg L−1
indicating improvement in energy efficiency and effluent quality of the AnMBR. The
location of cathode did not influence permeate fluxes and current densities, but permeate
pH was largely affected. Electrochemical cleaning improved permeate fluxes more than
2-fold (18.9 L m−2 hr−1 after 7 days of operation) compared to the operation of the
0.1μm membrane without a cleaning procedure. Application of a turbulence promotor
increased permeate fluxes and current densities in filtering anode. The hybrid anode
resulted in similar current densities, but higher permeate fluxes as compared to the
filtering anode, which dropped below 20 L m−2 hr−1 only after 8 days of operation. The
Kocatürk-Schumacher et al. Microbial Anode Combined With AnMBR
hybrid anode configuration is an attractive option that combines high permeate fluxes on
conventional non-conductive filters with current generation on an inexpensive conductive
material. In summary, our results demonstrate that combining BES with AnMBR is a
promising approach toward an energy efficient wastewater treatment. back to the year overview M. Bühler, C. Klose, F. Hegge, T. Lickert, S. ThieleA Novel Fabrication Technique for Electrodes of PEM Water Electrolyzers 2017 ECS Transactions , volume : 80, pages : 1069 - 1075» show abstract « hide abstract Abstract In this work the improvement of material interfaces at electrodes for proton exchange membrane (PEM) water electrolyzers is addressed by a novel fabrication technique. In this approach the electrode and the membrane are directly deposited on the porous transport layers (PTLs), which serve as substrate for the electrodes. The aim is to stabilize and increase the oxygen and hydrogen evolution rate at high current densities leading to a reduction of the noble metal loading of the electrodes – and additionally to develop a cost effective novel fabrication technique applicable for the large scale industrial fabrication of electrodes for PEM water electrolyzers. The innovative manufacturing technique is described in this transaction, and current challenges regarding the coating of porous substrates in terms of parameter control, reliability and homogeneity are pointed out. M. Breitwieser, T. Bayer, A. Büchler, R. Zengerle, S. M. Lyth, S. ThieleA fully spray-coated fuel cell membrane electrode assembly using Aquivion ionomer with a graphene oxide/cerium oxide interlayer 2017 J Power Sources , volume : 351, pages : 145 - 150» show abstract « hide abstract Abstract A novel multilayer membrane electrode assembly (MEA) for polymer electrolyte membrane fuel cells
(PEMFCs) is fabricated in this work, within a single spray-coating device. For the first time, direct
membrane deposition is used to fabricate a PEMFC by spraying the short-side-chain ionomer Aquivion
directly onto the gas diffusion electrodes. The fully sprayed MEA, with an Aquivion membrane 10 mm in
thickness, achieved a high power density of 1.6 W/cm2 for H2/air operation at 300 kPaabs. This is one of
the highest reported values for thin composite membranes operated in H2/air atmosphere. By the means
of confocal laser scanning microscopy, individual carbon fibers from the gas diffusion layer are identified
to penetrate through the micro porous layer (MPL), likely causing a low electrical cell resistance in the
range of 150 U cm2 through the thin sprayed membranes. By spraying a 200 nm graphene oxide/cerium
oxide (GO/CeO2) interlayer between two layers of Aquivion ionomer, the impact of the electrical short is
eliminated and the hydrogen crossover current density is reduced to about 1 mA/cm2. The peak power
density of the interlayer-containing MEA drops only by 10% compared to a pure Aquivion membrane of
similar thickness. N. Borst, F. Schuler, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, M. Trotter, A. B. Rodríguez-Martínez, N. Paust, R. Zengerle, F. von StettenA technology platform for digital nucleic acid diagnostics at the point of care 2017 Laboratoriumsmedizin , volume : 41, issue : 5» show abstract « hide abstract Abstract The combination of digital amplification and centrifugal microfluidics can enable quantitative and fast diagnostics at the point of care (PoC). The new unit operation of centrifugal step emulsification allows high throughput droplet generation. Different methods for digital nucleic acid analysis, including PCR, recombinase polymerase amplification (RPA) and loop mediated isothermal amplification (LAMP), have already been demonstrated. Our novel approach of integrated sample-to-answer analysis is introduced, and examples for the detection of HIV and single cell analysis of antibiotic resistant bacteria are presented. Next to these LabDisk based systems, a microfluidic cartridge termed DropChip allows for digital amplification using only commercially available laboratory devices. L. Benning, L. Gutzweiler, K. Tröndle, J. Riba, R. Zengerle, P. Koltay, S. Zimmermann, G. B. Stark, G. FinkenzellerAssessment of hydrogels for bioprinting of endothelial cells 2017 J Biomed Mater Res A , pages : 935 - 947» show abstract « hide abstract Abstract In tissue engineering applications, vascularization can be accomplished by co-implantation of
tissue forming cells and endothelial cells (ECs), whereby the latter are able to form functional
blood vessels. The use of three-dimensional (3D) bioprinting technologies has the potential to
improve the classical tissue engineering approach because these will allow the generation of
scaffolds with high spatial control of endothelial cell allocation. This study focuses on a side
by side comparisons of popular commercially available bioprinting hydrogels (matrigel,
fibrin, collagen, gelatin, agarose, Pluronic F-127, alginate and alginate/gelatin) in the context
of their physicochemical parameters, their swelling/degradation characteristics, their
biological effects on vasculogenesis-related EC parameters and their printability. The aim of
this study was to identify the most suitable hydrogel or hydrogel combination for inkjet
printing of ECs to build pre-vascularized tissue constructs. Most tested hydrogels displayed
physicochemical characteristics suitable for inkjet printing. However, Pluronic F-127 and the
alginate/gelatin blend were rapidly degraded when incubated in cell culture medium. Agarose,
Pluronic F-127, alginate and alginate/gelatin hydrogels turned out to be unsuitable for
bioprinting of ECs because of their non-adherent properties and/or their incapability to
support EC proliferation. Gelatin was able to support EC proliferation and viability but was
unable to support endothelial cell sprouting. Our experiments revealed fibrin and collagen to
be most suitable for bioprinting of ECs, because these hydrogels showed acceptable
swelling/degradation characteristics, supported vasculogenesis-related EC parameters and
showed good printability. Moreover, ECs in constructs of preformed spheroids survived the
printing process and formed capillary-like cords. T. Gleichmann, A. Rostas, J. Wörner, E. Schleicher, L. Gutzweiler, B. Hamouda, R. Zengerle, P. Koltay, L. RieggerAtmospheric Photopolymerization of Acrylamide Enabled by Aqueous Glycerol Mixtures: Characterization and Application for Surface-Based Microfluidics 2017 Macromol Mater Eng , page : 1600518» show abstract « hide abstract Abstract Polyacrylamide usually is the material of choice for electrophoretic separation in slab gels, capillaries, and microfluidic devices. So far its polymerization requires anaerobic environments because oxygen impurities inhibit or even terminate the polymerization reaction of acrylamide. Here, it is demonstrated that gel precursor solutions with glycerol contents above 20 vol% enable direct atmospheric photopolymerization of acrylamide with no need for sealing or degassing the solution in advance. The positive effect of glycerol on the polymerization reaction is proven by simulation-validated electron paramagnetic resonance measurements. Nuclear magnetic resonance reveals that glycerol does not interfere with the reaction indicating that the observed enhancement in polymerization is owed to the low oxygen solubility of aqueous glycerol mixtures. Glycerol concentrations of >60 vol% in the gel precursor solution enable complete polymerization of volumes down to 5 nL within less than 5 s. This enables using liquid handling robots to fabricate channel-free open microfluidic structures of solid polyacrylamide hydrogel in a low-cost automated manner in a standard lab environment. Y. Zhao, G. Czilwik, V. Klein, K. Mitsakakis, R. Zengerle, N. PaustC-reactive protein and Interleukin 6 microfluidic immunoassays
with on-chip pre-stored reagents and centrifugo-pneumatic liquid control 2017 Lab Chip , volume : 17, issue : 9, pages : 1666 - 1677» show abstract « hide abstract Abstract We present a fully automated centrifugal microfluidic method for particle based protein immunoassays. Stick-pack
technology is employed for pre-storage and release of liquid reagents. Quantitative layout of centrifugo-pneumatic
particle handling, including timed valving, switching and pumping is assisted by network simulations. The automation is
exclusively controlled by the spinning frequency and does not require any additional means. New centrifugal microfluidic
process chains are developed in order to sequentially supply wash buffer based on frequency dependent stick-pack
opening and pneumatic pumping to perform two washing steps from one stored wash buffer; pre-store and re-suspend
functionalized microparticles on disk; and switch between the path of the waste fluid and the path of the substrate
reaction product with 100% efficiency. The automated immunoassay concept comprises on demand ligand binding, two
washing steps, substrate reaction, timed separation of the reaction products, and termination of the substrate reaction.
We demonstrated separation of particles from three different liquids with particle loss below 4 % and residual liquid
remaining within particles below 3 %. The automated immunoassay concept was demonstrated by means of detecting Creactive
protein (CRP) in the range of 1 - 81 ng ml-1 and Interleukin 6 (IL-6) in the range of 64 - 13500 pg ml-1. The limit of
detection and quantification were 1.0 ng ml-1 and 2.1 ng ml-1 for CRP; 64 pg ml-1 and 205 pg ml-1 for IL-6, respectively. M. Breitwieser, C. Klose, A. Hartmann, A. Büchler, M. Klingele, S. Vierrath, R. Zengerle, S. ThieleCerium Oxide Decorated Polymer Nanofibers as Effective
Membrane Reinforcement for Durable, High-Performance
Fuel Cells
2017 Adv Energy Mater , page : 1602100» show abstract « hide abstract Abstract High-power, durable composite fuel cell membranes are fabricated here by
direct membrane deposition (DMD). Poly(vinylidene fluoride-co-hexafluo-
ropropylene) (PVDF-HFP) nanofibers, decorated with CeO
2
nanoparticles
are directly electrospun onto gas diffusion electrodes. The nanofiber mesh
is impregnated by inkjet-printed Nafion ionomer dispersion. This results in
12 µm thin multicomponent composite membranes. The nanofibers provide
membrane reinforcement, whereas the attached CeO
2
nanoparticles promote
improved chemical membrane durability due to their radical scavenging
properties. In a 100 h accelerated stress test under hot and dry conditions,
the reinforced DMD fuel cell shows a more than three times lower voltage
decay rate (0.39 mV h
−1
) compared to a comparably thin Gore membrane
(1.36 mV h
−1
). The maximum power density of the DMD fuel cell drops by
9%, compared to 54% measured for the reference. Impedance spectroscopy
reveals that ionic and mass transport resistance of the DMD fuel cell are
unaffected by the accelerated stress test. This is in contrast to the reference,
where a 90% increase of the mass transport resistance is measured. Energy
dispersive X-ray spectroscopy reveals that no significant migration of cerium
into the catalyst layers occurs during degradation. This proves that the PVDF-
HFP backbone provides strong anchoring of CeO
2
in the membrane. P. Lettenmeier, S. Kolb, L. Zielke, S. Thiele, A. Fallisch, N. Sata, A. S. Gago, K. A. FriedrichComprehensive investigation of novel pore-graded gas diffusion layers for high-performance and cost-effective proton exchange membrane electrolyzers 2017 Energy Environ. Sci. , volume : 10, pages : 2521 - 2533» show abstract « hide abstract Abstract Hydrogen produced by water electrolysis is a promising storage medium for renewable energy. Reducing the capital cost of proton exchange membrane (PEM) electrolyzers without losing efficiency is one of its most pressing challenges. Gas diffusion layers (GDL), such as felts, foams, meshes and sintered plates, are key stack components, but these are either inefficient or expensive. This study presents a new type of GDL produced via vacuum plasma spraying (VPS), which offers a large potential for cost reduction. With this technology, it is possible to introduce a gradient in the pore-size distribution along the thickness of the GDL by varying the plasma parameters and titanium powder particle sizes. This feature was confirmed by cross-section scanning electron microscopy (SEM). X-ray computed tomography (CT) and mercury intrusion porosimetry allowed determining the porosity, pore radii distribution, and pore entry distribution. Pore radii of ca. 10 μm could be achieved in the layers of the GDL close to the bipolar plate, while those in contact with the electrodes were in the range of 5 μm. The thermally sprayed Ti-GDLs allowed achieving PEM electrolyzer performances comparable to those of the state-of-the-art sintered plates and far superior than those of meshes. Moreover, a numerical model showed that the reduced capillary pressure and tortuosity eliminates mass transport limitations at 2 A cm−2. The results presented herein demonstrate a promising solution to reduce the cost of one of the most expensive components of the stack. L. Benning, L. Gutzweiler, K. Tröndle, J. Riba, R. Zengerle, P. Koltay, S. Zimmermann, G.B. Stark, G. FinkenzellerCytocompatibility testing of hydrogels toward bioprinting of mesenchymal stem cells 2017 J Biomed Mater Res A , volume : 105, pages : 3231 - 3241» show abstract « hide abstract Abstract Mesenchymal stem cells (MSCs) represent a very attractive cell source for tissue engineering applications aiming at the generation of artificial bone substitutes. The use of three-dimensional bioprinting technologies has the potential to improve the classical tissue engineering approach because bioprinting will allow the generation of hydrogel scaffolds with high spatial control of MSC allocation within the bioprinted construct. In this study, we have performed direct comparisons between commercially available hydrogels in the context of their cytocompatibility toward MSCs and their physicochemical parameters with the aim to identify the most suitable hydrogel for drop-on-demand (DoD) printing of MSCs. In this context, we examined matrigel, fibrin, collagen, gelatin, and gelatin/alginate at various hydrogel concentrations. Matrigel, fibrin, collagen, and gelatin were able to support cell viability, but the latter showed a limited potential to promote MSC proliferation. We concentrated our study on fibrin and collagen hydrogels and investigated the effect of hydroxyapatite (HA) inclusion. The inclusion of HA enhanced proliferation and osteogenic differentiation of MSCs and prevented degradation of fibrin in vitro. According to viscosity and storage moduli measurements, HA-blends displayed physicochemical characteristics suitable for DoD printing. In bioprinting experiments, we confirmed that fibrin and collagen and their respective HA-blends represent excellent hydrogels for DoD-based printing as evidenced by high survival rates of printed MSCs. C. Klose, M. Breitwieser, S. Vierrath, M. Klingele, H. Cho, A. Büchler, J. Kerres, S. ThieleElectrospun sulfonated poly(ether ketone) nanofibers as proton conductive reinforcement for durable Nafion composite membranes 2017 J Power Sources , volume : 361, pages : 237 - 242» show abstract « hide abstract Abstract We show that the combination of direct membrane deposition with proton conductive nanofiber reinforcement yields highly durable and high power density fuel cells. Sulfonated poly(ether ketone) (SPEK) was directly electrospun onto gas diffusion electrodes and then filled with Nafion by inkjet-printing resulting in a 12 μm thin membrane. The ionic membrane resistance (30 mΩ*cm2) was well below that of a directly deposited membrane reinforced with chemically inert (PVDF-HFP) nanofibers (47 mΩ*cm2) of comparable thickness. The power density of the fuel cell with SPEK reinforced membrane (2.04 W/cm2) is 30% higher than that of the PVDF-HFP reinforced reference sample (1.57 W/cm2). During humidity cycling and open circuit voltage (OCV) hold, the SPEK reinforced Nafion membrane showed no measurable degradation in terms of H2 crossover current density, thus fulfilling the target of 2 mA/cm2 of the DOE after degradation. The chemical accelerated stress test (100 h OCV hold at 90 °C, 30% RH, H2/air, 50/50 kPa) revealed a degradation rate of about 0.8 mV/h for the fuel cell with SPEK reinforced membrane, compared to 1.0 mV/h for the PVDF-HFP reinforced membrane. K. Lehmann, O. Yurchenko, A. Heilemann, S. Vierrath, L. Zielke, S. Thiele, A. Fischer, G. UrbanHigh surface hierarchical carbon nanowalls synthesized by plasma deposition using an aromatic precursor 2017 Carbon , volume : 118, pages : 578 - 587» show abstract « hide abstract Abstract Hierarchical carbon nanowalls (CNW) are synthesized by plasma-enhanced chemical vapor deposition using p-xylene as a complex precursor. In contrast to ordinary CNW, synthesized with short-chained carbons, hierarchical CNW show a unique multi-scale pore structure, made up of micro- and mesopores connected by tubular macropores, offering higher surface area and surface accessibility. Their morphology, graphitic structure, surface area and accessibility are verified by transmission and scanning electron microscopy, gas sorption and impedance spectroscopy. Focused ion beam scanning electron microscopy tomography demonstrates the presence of macropores ensuring pore connectivity down to the substrate. Nitrogen/krypton physisorption confirms the micro- and mesoporous structure contributing extensively to the surface area. The impedance spectra are evaluated according to standard RC and transmission line models. The sample deposited for 60 min, with a structure height of 4.75 μm, features a volumetric capacitance of 2.6 F cm−3 and a response time of 25 ms. Hierarchical CNW exhibit a two to six times higher volumetric capacitance than CNW of similar proportions, reported in literature. Hierarchical CNW offer a promising way to realize high power and energy density requirements in electrochemical energy systems, like supercapacitors, due to their good conductivity, high surface area and open pore structure. A. Fallisch, L. Schellhase, J. Fresko, M. Zedda, J. Ohlmann, M. Steiner, A. Bösch, L. Zielke, S. Thiele, F. Dimroth, T. SmolinkaHydrogen concentrator demonstrator module with 19.8% solar-to-hydrogen conversion efficiency according to the higher heating value 2017 Int J Hydrogen Energ , pages : 26804 - 26815» show abstract « hide abstract Abstract Renewable hydrogen is a key element to a sustainable energy system of the future. Therefore solar hydrogen generation has been investigated by various research groups in recent years. The patented concept of the Hydrogen Concentrator (HyCon), which combines III-V multi-junction solar cells with polymer electrolyte membrane electrolysis, has been constantly developed over the last years. In this work, a unique weatherproof HyCon module with an area of 8 × 90.7 cm2 was build and characterized in an outdoor measurement for over two month. During this measurement period, the module showed a stable operation regardless of the water volume flow. The module works under natural convection without any circulation pumps at a suitable maximum temperature of 60–70 °C. The HyCon module consists of eight individual units (HyCon cells), each combining a photovoltaic and an electrolysis cell. Some of the HyCon cells reach a solar-to-hydrogen conversion efficiency of 20% according to the higher heating value at high current densities of 0.8 A/cm2. On the module level a maximum efficiency of 19.8% is reached. To the best of our knowledge this is the highest conversion efficiency so far achieved at such high current densities using a dual junction solar cell. A. Fallisch, L. Schellhase, J. Fresko, M. Zechmeister, M. Zedda, J. Ohlmann, L. Zielke, N. Paust, T. SmolinkaInvestigation on PEM water electrolysis cell design
and components for a HyCon solar hydrogen
generator 2017 Int J Hydrogen Energ , volume : 42, pages : 13544 - 13553» show abstract « hide abstract Abstract Hydrogen as a secondary energy carrier promises a large potential as a long term storage
for fluctuating renewable energies. In this sense a highly efficient solar hydrogen generation
is of great interest especially in southern countries having high solar irradiation. The
patented Hydrogen Concentrator (HyCon) concept yields high efficiencies combining
multi-junction solar cells with proton exchange (PEM) membrane water electrolysis. In this
work, a special PEM electrolysis cell for the HyCon concept was developed and investigated.
It is shown that the purpose-made PEM cell shows a high performance using a titanium
hybrid fiber sinter function both as a porous transport layer and flow field. The
electrolysis cell shows a high performance with 1.83 V at 1 A/cm2 and 24 °C working under
natural convection with a commercially available catalyst coated membrane. A theoretical
examination predicts a total efficiency for the HyCon module from sunlight to hydrogen of
approximately 19.5% according to the higher heating value. L. Gutzweiler, S. Kartmann, K. Troendle, L. Benning, G. Finkenzeller, R. Zengerle, P. Koltay, B. Stark, S. ZimmermannLarge scale production and controlled deposition of single HUVEC spheroids for bioprinting applications 2017 Biofabrication , volume : 9 (2), page : 02502» show abstract « hide abstract Abstract We present 1.) a fast and automated method for large scale production of HUVEC spheroids based on the hanging drop method and 2.) a novel method for well-controlled lateral deposition of single spheroids by drop-on-demand printing. Large scale spheroid production is achieved via printing 1536 droplets of HUVEC cell suspension having a volume of 1 µl each within 3 minutes at a pitch of 2.3 mm within an array of 48 x 32 droplets onto a flat substrate. Printing efficiencies between 97.9% and 100% and plating efficiencies between 87.3% and 100% were achieved. Harvested spheroids (consisting of approx. 250 HUVECs each) appear uniform in size and shape. After incubation and harvesting, the spheroids are deposited individually in user-defined patterns onto hydrogels using an automated drop-on-demand dispenser setup. Controlled by an image detection algorithm focusing the dispenser nozzle, droplets containing exactly one spheroid are printed onto a substrate, while all other droplets are discarded. Using this approach an array of 6 x 3 HUVEC spheroids with intermediate distances of 500 µm embedded in fibrin was generated. Successful progress of spheroid sprouting and merging of neighboring sprouts was observed during the first 72 hours of incubation indicating a good viability of the deposited spheroids. M. Kokko, F. Bayerköhler, J. Erben, R. Zengerle, P. Kurz, S. KerzenmacherMolybdenum sulphides on carbon supports as electrocatalysts for hydrogen evolution in acidic industrial wastewater 2017 Appl Energ , volume : 190, pages : 1221 - 1233» show abstract « hide abstract Abstract Microbial electrolysis cells (MECs) are an attractive future alternative technology to generate renewable
hydrogen and simultaneously treat wastewaters. The thermodynamics of hydrogen evolution in MECs
can be greatly improved by operating the cathode at acidic pH in combination with a neutral pH microbial
anode. This can easily be achieved with acidic industrial wastewaters that have to be neutralised
before discharge. For the hydrogen evolution reaction (HER) in acidic wastewater, efficient and inexpensive
catalysts are required that are compatible with the often complex chemical composition of wastewaters.
In this study, molybdenum sulphides (MoSx) on different carbon supports were successfully used
for hydrogen evolution in different acidic media. At first, the cathodes were screened by linear sweep
voltammetry in sulphuric acid (pH 0) or phosphate buffer (pH 2.2). After this, the overpotentials for H2
production of the best cathodes and their long term performances (>=1 week) were determined in acidic
industrial wastewater (pH 2.4) obtained from a plant mainly producing cellulose acetate. For the most
promising MoSx cathodes, the overpotentials for HER (at 3 mA cm-2) were only ~40 mV higher than
for a platinum electrode. Most importantly, the catalytic efficiency of the MoSx electrodes improved in
the wastewater over time (7–17 days), while Pt electrodes were found to be slowly deactivated. Thus,
MoSx emerges as an affordable, efficient and especially durable electrocatalyst for HER in real acidic
wastewaters and this could be an important contribution to take energy production from wastewaters
in the form of hydrogen towards practical applications. M. Klingele, R. Moroni, S. Vierrath, S. ThieleMultiscale Tomography-Based Analysis of Fuel Cells: Towards a Fully Resolved Fuel Cell Reconstruction 2017 J Electrochem Energy , volume : 15, page : 014701» show abstract « hide abstract Abstract The microstructure of a fuel cell electrode largely determines the performance of the whole fuel cell system. In this regard, tomographic imaging is a valuable tool for the understanding and control of the electrode morphology. The distribution of pore- and feature-sizes within fuel cell electrodes covers several orders of magnitude, ranging from millimeters in the gas diffusion layer down to few nanometers in the catalyst layer. This obligates the application of various tomographic methods for imaging every aspect of a fuel cell. This perspective evaluates the capabilities, limits and challenges of each of these methods. Further it highlights and suggests efforts towards the integration of multiple tomographic methods into single multiscale datasets, a venture which aims at large scale, and morphologically fully resolved fuel cell reconstructions. M. Frei, J. Erben, J. Martin, R. Zengerle, S. KerzenmacherNanofiber-deposited porous platinum enables glucose fuel cell anodes with high current density in body fluids 2017 J Power Sources , volume : 362, pages : 168 - 173» show abstract « hide abstract Abstract The poisoning of platinum anodes by body-fluid constituents such as amino acids is currently the main hurdle preventing the application of abiotic glucose fuel cells as battery-independent power supply for medical implants. We present a novel anode material that enables continuous operation of glucose oxidation anodes in horse serum for at least 30 days at a current density of (7.2 ± 1.9) μA cm−2. The fabrication process is based on the electro-deposition of highly porous platinum onto a 3-dimensional carbon nanofiber support, leading to approximately 2-fold increased electrode roughness factors (up to 16500 ± 2300). The material's superior performance is not only related to its high specific surface area, but also to an improved catalytic activity and/or poisoning resistance. Presumably, this results from the micro- and nanostructure of the platinum deposits. This represents a major step forward in the development of implantable glucose fuel cells based on long-term stable platinum electrodes. S. Zehnle, M. Rombach, R. Zengerle, F. von Stetten, N. PaustNetwork simulation-based optimization of centrifugo-pneumatic blood plasma separation 2017 Biomicrofluidics , volume : 11, page : 024114» show abstract « hide abstract Abstract Automated and robust separation of 14 ll of plasma from 40 ll of whole blood at a
purity of 99.81%60.11% within 43 s is demonstrated for the hematocrit range of
20%–60% in a centrifugal microfluidic polymer disk. At high rotational frequency,
red blood cells (RBCs) within whole blood are concentrated in a radial outer RBC
collection chamber. Simultaneously, plasma is concentrated in a radial inner
pneumatic chamber, where a defined air volume is enclosed and compressed.
Subsequent reduction of the rotational frequency to not lower than 25 Hz enables
rapid transfer of supernatant plasma into a plasma collection chamber, with highly
suppressed resuspension of red blood cells. Disk design and the rotational protocol
are optimized to make the process fast, robust, and insusceptible for undesired cell
resuspension. Numerical network simulation with lumped model elements is
used to predict and optimize the fluidic characteristics. Lysis of the remaining
red blood cells in the purified plasma, followed by measurement of the hemoglobin
concentration, was used to determine plasma purity. Due to the pneumatic
actuation, no surface treatment of the fluidic cartridge or any additional external
means are required, offering the possibility for low-cost mass fabrication technologies,
such as injection molding or thermoforming. L. Gutzweiler, T. Gleichmann, L. Tanguy, P. Koltay, R. Zengerle, L. Riegger, , , Open microfluidic gel electrophoresis: Rapid and low cost separation and analysis of DNA at the nanoliter scale 2017 Electrophoresis , volume : 38, pages : 1764 - 1770» show abstract « hide abstract Abstract Gel electrophoresis is one of the most applied and standardized tools for separation and analysis of
macromolecules and their fragments in academic research and in industry. In this work we present a
novel approach for conducting on-demand electrophoretic separations of DNA molecules in open
microfluidic (OM) systems on planar polymer substrates. The approach combines advantages of slab
gel, capillary- & chip-based methods offering low consumable costs (< 0.1 $) circumventing cost intensive microfluidic chip fabrication, short process times (5 minutes per analysis) and high
sensitivity (4 ng/µl dsDNA) combined with reasonable resolution (17 bases). The open microfluidic
separation system comprises two opposing reservoirs of 2-4 µl in volume, a semi-contact written gel
line acting as separation channel interconnecting the reservoirs and sample injected into the line via
non-contact droplet dispensing and thus enabling the precise control of the injection plug and sample
concentration. Evaporation is prevented by covering aqueous structures with PCR-grade mineral oil
while maintaining surface temperature at 15°C. The liquid gel line exhibits a semi-circular cross
section of adaptable width (~200-600 µm) and height (~30-80 µm) as well as a typical length of 15-55
mm. Layout of such liquid structures is adaptable on-demand not requiring time consuming and
repetitive fabrication steps. The approach was successfully demonstrated by the separation of a
standard label-free DNA ladder (100-1000 bp) at 100 V/cm via in-line staining and laser induced
fluorescent end-point detection using an automated prototype. J. Madjarov, S.C. Popat, J. Erben, A. Götze, R. Zengerle, S. KerzenmacherRevisiting methods to characterize bioelectrochemical systems: The influence of uncompensated resistance (iRu-drop), double layer capacitance, and junction potential 2017 J Power Sources , volume : 356, pages : 408 - 418» show abstract « hide abstract Abstract Bioelectrochemical systems (BES) are characterized with methods derived from the electrochemistry field, for e.g. linear sweep voltammetry (LSV), cyclic voltammetry (CV), and chronoamperometry. The limitations of electrochemical measurements are well known and described, but there are new challenges when these are applied to biological systems. For instance, the electrolyte conditions are predefined by the application involving the use of low conductivities, leading to an increase of two error sources: the iRu-drop and junction potential. Furthermore, the use of electrodes with high surface areas and thus high double layer capacitance lead to capacitive currents that superimpose the biocatalytic current of interest. Even though these problems have often been mentioned in the bioelectrochemistry field, they are seldom considered and reported in publications. The scope of this work is to present and discuss methods to quantify the Ru and double layer capacitance, and to demonstrate their significant influence on the recording of polarization curves. In a typical BES setup, it is exemplarily shown that due to iRu-drop measured potentials can deviate by more than 200 mV from the actual potential. Similarly, more than 40% of a recorded electrode current can originate from the electrode material's double layer capacitance. M. Keller, G. Czilwik, J. Schott, I. Schwarz, K. Dormanns, F. von Stetten, R. Zengerle, N. PaustRobust temperature change rate actuated valving and switching for highly integrated centrifugal microfluidics 2017 Lab Chip , volume : 17, pages : 864 - 875» show abstract « hide abstract Abstract We present new unit operations for valving and switching in centrifugal microfluidics that are actuated by a temperature change rate (TCR) and controlled by the rotational frequency. Implementation is realized simply by introducing a comparatively large fluidic resistance to an air vent of a fluidic structure downstream of a siphon channel. During temperature decrease at a given TCR, air pressure inside the downstream structure decreases and the fluidic resistance of the air vent slows down air pressure compensation allowing for a thermally induced underpressure to build up temporarily. Thereby the rate of temperature change determines the time course of the underpressure for a given geometry. The thermally induced underpressure pulls liquid against a centrifugal counterpressure above a siphon crest, which triggers the valve or switch. The centrifugal counterpressure (adjusted by rotation) serves as independent control parameter to allow or prevent valving or switching at any TCR. The unit operations are thus compatible to any temperature or centrifugation protocol prior to valving or switching. In contrast to existing methods, this compatibility is achieved at no additional costs: neither additional fabrication steps, nor additional disk space or external means are required besides global temperature control, which is per se needed for the assay. For layout, an analytical model is provided and verified. The TCR actuated unit operations are demonstrated, first, by a stand-alone switch that routes liquid to either one of the two collection chambers (n = 6) and, second, by studying robustness of TCR actuated valving within a microfluidic cartridge for highly integrated nucleic acid testing. Valving could safely be prevented during PCR by compensating the thermally induced underpressure of 3.52 kPa by centrifugal counterpressure at a rotational frequency of 30 Hz with a minimum safety range to valving of 2.03 kPa. Subsequently, a thermally induced underpressure of 2.55 kPa was utilized for robust siphon valving at 3 Hz with a minimum safety range of 2.32 kPa. M. Breitwieser, C. Klose, M. Klingele, A. Hartmann, J. Erben, H. Cho, J. Kerres, R. Zengerle, S. ThieleSimple fabrication of 12 μm thin nanocomposite fuel cell membranes by direct electrospinning and printing 2017 J Power Sources , volume : 337, pages : 137 - 144» show abstract « hide abstract Abstract Direct membrane deposition (DMD) was recently introduced as a novel polymer electrolyte membrane
fabrication method. Here, this approach is extended to fabricate 12 μm thin nanocomposite fuel cell membranes.
Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers are directly electrospun
onto gas diffusion electrodes. By inkjet-printing Nafion ionomer dispersion into the pore space of PVDF-HFP
nanofiber mats, composite membranes of 12 mm thickness were fabricated. At 120 C and 35% relative humidity,
stoichiometric 1.5/2.5 H2/air flow and atmospheric pressure, the power density of the DMD fuel cell
(0.19Wcm-2), was about 1.7 times higher than that of the reference fuel cell (0.11Wcm-2) with Nafion HP
membrane and identical catalyst. A lower ionic resistance and, especially at 120 C, a reduced charge transfer
resistance is found compared to the Nafion HP membrane. A 100 h accelerated stress test revealed a voltage
decay of below 0.8 mV h-1, which is in the range of literature values for significantly thicker reinforced
membranes. Finally, this novel fabrication approach enables new degrees of freedom in the design of
complex composite membranes. The presented combination of scalable deposition techniques has the potential
to simplify and thus reduce cost of composite membrane fabrication at a larger scale. F. Sun, R. Moroni, K. Dong, H. Markötter, D. Zhou, A. Hilger, L. Zielke, R. Zengerle, S. Thiele, J. Banhart, I. MankeStudy of the Mechanisms of Internal Short
Circuit in a Li/Li Cell by Synchrotron X‑ray
Phase Contrast Tomography 2017 ACS Energy Lett. , volume : 2, pages : 94 - 104» show abstract « hide abstract Abstract Knowledge about degradation and failure of Li-ion
batteries (LIBs) is of paramount importance, especially because failure
can be accompanied by severe hazards. To contribute to the
understanding of such phenomena, synchrotron in-line phase contrast
X-ray tomography was employed to investigate internal cell
deformation and degradation caused by an internal short circuit
(ISC). The tomographic images taken from an uncycled Li/Li cell and a
short-circuited Li/Li cell reveal how lithium microstructures (LmSs)
develop during electrochemical stripping and plating during discharge
and charge and how the three-layer separator used is damaged by
growing LmSs and delaminates and melts as a consequence of an ISC.
Previously unknown insights into the internal cell degradation and
deformation mechanisms caused by an ISC are obtained and provide
hints of how the properties of the separator could be modified to
improve the reliability and safety of current- and next-generation LIBs. M. Klingele, C. Pham, K. Rao Vuyyurud, B. Britton, S. Holdcroft, A. Fischer, S. ThieleSulfur doped reduced graphene oxide as metal-free catalyst for the oxygen reduction reaction in anion and proton exchange fuel cells 2017 Electrochem Commun , volume : 77, pages : 71 - 75» show abstract « hide abstract Abstract Sulfur doped reduced graphene oxide (S-rGO) is investigated for catalytic activity towards the oxygen reduction reaction (ORR) in acidic and alkaline electrolytes. X-ray photoelectron spectroscopy shows that sulfur in S-rGO is predominantly integrated as thiophene motifs within graphene sheets. The overall sulfur content is determined to be approximately 2.2 at.% (elemental analysis). The catalytic activity of S-rGO towards the ORR is investigated by both rotating disc electrode (RDE) and polymer electrolyte fuel cell (PEFC) measurements. RDE measurements reveal onset potentials of 0.3 V and 0.74 V (vs. RHE) in acidic and alkaline electrolyte, respectively. In a solid electrolyte fuel cell with S-rGO as cathode material, this is reflected in an open circuit voltage of 0.37 V and 0.78 V and a maximum power density of 1.19 mW/cm2 and 2.38 mW/cm2 in acidic and alkaline polymer electrolyte, respectively. This is the first report investigating the catalytic activity of a sulfur doped carbon material in both acidic and alkaline liquid electrolyte, as well as in both proton and anion exchange polymer electrolyte fuel cells. M. Breitwieser, M. Klingele, S. Vierrath, R. Zengerle, S. ThieleTailoring the membrane-electrode interface in PEM fuel cells: A review and perspective on novel engineering approaches 2017 Adv Energy Mater , page : 1701257 C. Van Pham, M. Klingele, B. Britton, K. R. Vuyyuru, T. Unmuessig, S. Holdcroft, A. Fischer,, S. ThieleTridoped Reduced Graphene Oxide as a Metal-Free Catalyst
for Oxygen Reduction Reaction Demonstrated in Acidic and
Alkaline Polymer Electrolyte Fuel Cells 2017 Advanced Sustainable Systems , volume : 1, page : 1600038» show abstract « hide abstract Abstract Recently, it has been demonstrated that doping of graphene by elements such
as N, S, or F creates active sites for the oxygen reduction reaction (ORR).
This results from bond polarization caused by the difference in electron-
egativity between heteroatom dopants and carbon, and/or the presence of
defects within the graphene lattice. In this work, fluorine, nitrogen, and sulfur
tridoped reduced graphene oxide (F,N,S-rGO) is designed to combine these
catalytically active sites. F,N,S-rGO can be inexpensively synthesized by a
facile and scalable route involving pyrolysis at 600 °C of sulfur-doped rGO
in the presence of Nafion and dimethyl formamide (DMF). The pyrolysis of
Nafion and DMF provides F
•
and N
•
radicals which serve as doping agents.
Rotating disk electrode investigations reveal the ORR catalytic activities of
F,N,S-rGO in both acidic and alkaline media, which are consistent with the
real performances of the respective polymer electrolyte fuel cells (PEFCs).
Maximum power densities of 14 and 46 mW cm
−2
are obtained for the acidic
and alkaline PEFCs, respectively, using F,N,S-rGO as ORR catalysts. To the
best of knowledge, this is the first report on the synthesis of F,N,S tridoped
rGO and on its ORR activity in both acidic and alkaline PEFCs. back to the year overview M. Hagner, J. M. Fritz, P. Alknes, C. Scheuerlein, L. Zielke, S. Vierrath, S. Thiele, B. Bordini, A. Ballarino3D Analysis of the Porosity in MgB2 Wires Using
FIB Nanotomography
2016 Ieee T Appl Supercon , volume : 26, page : 6200305» show abstract « hide abstract Abstract Porosity is one of several current limiting
mechanisms in MgB2 wires. We have compared the
microstructural homogeneity and the porosity distribution in
different ex situ and in situ MgB2 Powder-in-Tube (PIT) wires. The
sub-micrometer structure was determined using Focused Ion
Beam (FIB) nanotomography. The ex situ wires exhibit an
isotropic microstructure, which has been quantified in terms of an
identical tortuosity in transverse and longitudinal filament
direction. The very homogenous microstructure in the new ex situ
wire generation is probably one reason for its strongly improved
critical current density. The in situ wire has an anisotropic
microstructure with a lower tortuosity in the axial direction. The
microstructural inhomogeneity of the in situ filaments makes
microstructural characterization and the comparison between
materials and superconducting properties particularly
challenging. M. Klingele, B. Britton, M. Breitwieser, S. Vierrath, R. Zengerle, S. Holdcroft, S. ThieleA Completely Spray-Coated Membrane Electrode Assembly 2016 Electrochem Commun , volume : 70, pages : 65 - 68» show abstract « hide abstract Abstract We present a proton exchange membrane fuel cell (PEMFC) manufacturing route, in which a thin layer of polymer electrolyte solution is spray-coated on top of gas diffusion electrodes (GDEs) to work as a proton exchange membrane. Without the need for a pre-made membrane foil, this allows inexpensive, fast, large-scale fabrication of membrane-electrode assemblies (MEAs), with a spray-coater comprising the sole manufacturing device. In this work, a catalyst layer and a membrane layer are consecutively sprayed onto a fibrous gas diffusion layer with applied microporous layer as substrate. A fuel cell is then assembled by stacking anode and cathode half-cells with the membrane layers facing each other. The resultant fuel cell with a low catalyst loading of 0.1 mg Pt/cm2 on each anode and cathode side is tested with pure H2 and O2 supply at 80 °C cell temperature and 92% relative humidity at atmospheric pressure. The obtained peak power density is 1.29 W/cm2 at a current density of 3.25 A/cm2. By comparison, a lower peak power density of 0.93 W/cm2 at 2.2 A/cm2 is found for a Nafion NR211 catalyst coated membrane (CCM) reference, although equally thick membrane layers (approx. 25 μm), and identical catalyst layers and gas diffusion media were used. The superior performance of the fuel cell with spray-coated membrane can be explained by a decreased low frequency (mass transport) resistance, especially at high current densities, as determined by electrochemical impedance spectroscopy. W.E. Kaman, G. Elshout, P.J.E. Bindels, K. Mitsakakis, J.P. HaysCurrent problems associated with the
microbiological point-of-care testing of
respiratory tract infections in primary care 2016 Future Microbiol , volume : 11, pages : 607 - 610» show abstract « hide abstract Abstract Currently, the world is facing a potential ‘antibiotic apocalypse’, whereby clinically relevant bacteria are becoming increasingly resistant to all currently available antibiotics [1]. Several factors are contributing to this global increase in antibiotic resistance, including the unnecessary prescription of antibiotics for nonbacterial (viral and fungal) infections [2]. General practitioners (GPs) sit on the front line of antibiotic prescribing practice, having regular and broad-based contact with members of society that present to their offices with a range of disease states. One of the major reasons for visiting a GP is when a patient is apparently suffering from a respiratory tract infection [3]. The accurate diagnosis of the cause (i.e., the causative pathogen) of this infection can be difficult for the GP to make when only based on clinical symptoms. In the absence of sufficient diagnostic or clinical evidence, the GP may decide to prescribe antibiotics, or alternatively may withhold antibiotic therapy (suspecting a viral infection) when antibiotic therapy is actually required. On the one hand, the ‘overprescribing’ of antibiotics for nonbacterial infections may not only lead to the acquisition of antibiotic resistance in the resident flora of the patient, but also result in unnecessary healthcare costs for the patient and society [4]. It will also expose the patients to unwanted side effects from the antibiotic [5]. On the other hand, not prescribing antibiotics in case of a bacterial pneumonia, may result in extra morbidity for the patient and subsequent healthcare costs [6].
Access to point-of-care (POC) tests may reduce the prescription of antibiotics in primary care [7], although current POC testing performed by GPs for diagnosing respiratory tract infections tends to rely on the use of nonspecific biomarkers, such as CRP [8]. These biomarkers only provide information on the likelihood of a complicated (lower) respiratory tract infection being present. They do not identify pathogens or any antibiotic resistance that may be associated with a pathogen. For this reason, more advanced POC testing devices are currently being developed for specific use in the primary care environment. Such devices could potentially accurately diagnose the causative pathogen associated with a respiratory tract infection and any accompanying antibiotic resistance genes (if present), thereby potentially helping the GP to personalize their antibiotic prescribing practices to the needs of each patient.
Unfortunately, however, many hurdles currently exist to the successful implementation of infectious disease POC diagnostics into primary care, the most important of which are described below. F. Schuler, M. Trotter, M. Geltman, F. Schwemmer, S. Wadle, E. Domínguez-Garrido, M. López, C. Cervera-Acedo, P. Santibáñez, F. von Stetten, R. Zengerle, N. PaustDigital Droplet PCR on Disk 2016 Lab Chip , volume : 16, pages : 208 - 216» show abstract « hide abstract Abstract Existing systems for digital droplet PCR (ddPCR) either suffer from low integration or are difficult to introduce to mass fabrication. Here we present an integrated system that is compatible to mass fabrication and combines emulsification, PCR, and fluorescence readout in a single chamber within a disposable cartridge (disk). Droplets are generated by injecting the sample into fluorinated oil via centrifugal step emulsification. The resulting emulsion is aligned in the PCR and readout zone by capillary action. During thermocycling, gas bubbles generated by degassing are removed by capillary driven transport through tapered regions in the PCR chamber. Thereby, the positioning of the emulsion within the readout zone of the PCR chamber is ensured at any time and no bubbles are present during readout. Manual handling of the disk solely requires pipetting of oil and PCR mix into the inlet structures, placing the disk into the thermocycler and subsequently into a microarray scanner. The functionality of the ddPCR process chain is demonstrated by quantitative detection of the cystic fibrosis causing mutation p.Phe508del, which is of interest for non-invasive prenatal testing (NIPT). The mutation was detected in a concentration range spanning four orders of magnitude. We envision that this work will lay the base for the development of highly integrated sample-to-digital-answer PCR systems that can be employed in routine clinical diagnosis. F. Schuler, C. Siber, S. Hin, S. Wadle, N. Paust, R. Zengerle, F. von StettenDigital droplet LAMP as microfluidic App on standard laboratory devices 2016 Anal Methods-uk , volume : 8, pages : 2750 - 2755» show abstract « hide abstract Abstract Digital nucleic acid amplification methods are a growing research field that allows for absolute
quantification of DNA making the need of standard curves redundant. However, most existing digital
amplification systems require specialized laboratory devices and costly investments. The required
disposable cartridges are device specific and not interchangeable. Here, we present digital droplet loopmediated
isothermal amplification (ddLAMP) as a microfluidic App on standard laboratory devices.
ddLAMP is implemented on a disposable polymer chip (DropChip) of the format of a standard
microscope slide. After DNA denaturation off-chip the reaction mix is emulsified in the DropChip in a
mini-centrifuge in 6 minutes. The DropChip is transferred to an in situ thermal cycler for 1 hour of
incubation. Afterwards, a fluorescence scan in a microarray scanner is performed. The DropChip allows
for absolute quantification with a dynamic range of 15-1500 DNA copies μl-1. Assay conditions were
optimized for ddLAMP and comparison of ddPCR and ddLAMP for genomic E. coli DNA reveals very good
concordance. N. Wehkamp, M. Breitwieser, A. Büchler, M. Klingele, R. Zengerle, S. ThieleDirectly deposited Nafion/TiO2 composite membranes for high power medium temperature fuel cells 2016 Rsc Adv , volume : 6, pages : 24261 - 24266» show abstract « hide abstract Abstract This work presents a simple production method for TiO2 reinforced Nafion® membranes which are stable up to a 120 °C operation temperature. The novel TiO2 reinforced membranes yield a maximum power density of 2.02 W cm−2 at 120 °C; H2/O2; 0.5/0.5 L min−1; 90% RH, 300/300 kPaabs. This is 2.8 times higher than the highest power density for TiO2 reinforced membranes so far published in literature. The described membranes even exceed the maximum power density of a commercial Nafion® HP membrane in an identical measurement setup at 100 °C and 120 °C. Compared to the commercial Nafion® HP membrane the maximum power density was increased by 27% and 9% at 100 °C and 120 °C, respectively. The membrane is manufactured by drop-casting a dispersion of Nafion® and TiO2 nanoparticles onto both the anode and cathode gas diffusion electrodes. Furthermore pure Nafion® membranes manufactured by the same method had higher membrane resistances at temperatures >100 °C than TiO2-reinforced Nafion® membranes. X. Wu, N. Schneider, A. Platen, I. Mitra, R. Zengerle, R. Schüle, M. MeierIn situ characterization of the mTORC1 during adipogenesis of human adult stem cells on chip 2016 PNAS , volume : 113, pages : 4143 - 4150» show abstract « hide abstract Abstract Mammalian target of rapamycin (mTOR) is a central kinase in- tegrating nutrient, energy, and metabolite signals. The kinase forms two distinct complexes: mTORC1 and mTORC2. mTORC1 plays an essential but undefined regulatory function for regeneration of adipose tissue. Analysis of mTOR in general is hampered by the complexity of regulatory mechanisms, including protein interac- tions and/or phosphorylation, in an ever-changing cellular microen- vironment. Here, we developed a microfluidic large-scale integration chip platform for culturing and differentiating human adipose- derived stem cells (hASCs) in 128 separated microchambers under standardized nutrient conditions over 3 wk. The progression of the stem cell differentiation was measured by determining the lipid accumulation rates in hASC cultures. For in situ protein analytics, we developed a multiplex in situ proximity ligation assay (mPLA) that can detect mTOR in its two complexes selectively in single cells and implemented it on the same chip. With this combined technology, it was possible to reveal that the mTORC1 is regulated in its abundance, phosphorylation state, and localization in coordination with lyso- somes during adipogenesis. High-content image analysis and param- eterization of the in situ PLA signals in over 1 million cells cultured on four individual chips showed that mTORC1 and lysosomes are temporally and spatially coordinated but not in its composition during adipogenesis. M. Zeiger, S. Fleischmann, B. Krüner, A. Tolosa, S. Bechtel, M. Baltes, A. Schreiber, R. Moroni, S. Vierrath, S. Thiele, V. PresserInfluence of carbon substrate on the electrochemical performance of carbon/manganese oxide hybrids in aqueous and organic electrolytes 2016 Rsc Adv , volume : 6, pages : 107163 - 107» show abstract « hide abstract Abstract Manganese oxide presents very promising electrochemical properties as an electrode material in supercapacitors, but there remain important open questions to guide further development of the complex manganese oxide/carbon/electrolyte system. Our work addresses specifically the influence of carbon ordering and the difference between outer and inner porosity of carbon particles for the application in aqueous 1 M Na2SO4 and 1 M LiClO4 in acetonitrile. Birnessite-type manganese oxide was hydrothermally hybridized on two kinds of carbon onions with only outer surface area and different electrical conductivity, and conventional activated carbon with a high inner porosity. Carbon onions with a high degree of carbon ordering, high conductivity, and high outer surface area were identified as the most promising material, yielding 179 F g−1. Pore blocking in activated carbon yields unfavorable electrochemical performances. The highest specific energy of 16.4 W h kg−1 was measured for a symmetric full-cell arrangement of manganese oxide coated high temperature carbon onions in the organic electrolyte. High stability during 10 000 cycles was achieved for asymmetric full-cells, which proved as a facile way to enhance the electrochemical performance stability. F. Schwemmer, C. E. Blanchet, A. Spilotros, D. Kosse, S. Zehnle, H. D. T. Mertens, M. A. Graewert, M. Rössle, N. Paust, D. I. Svergun, F. von Stetten, R. Zengerle, D. MarkLabDisk for SAXS: a centrifugal microfluidic sample
preparation platform for small-angle X-ray
scattering 2016 Lab Chip , volume : 16, pages : 1161 - 1170» show abstract « hide abstract Abstract We present a centrifugal microfluidic LabDisk for protein structure analysis via small-angle X-ray scattering
(SAXS) on synchrotron beamlines. One LabDisk prepares 120 different measurement conditions, grouped
into six dilution matrices. Each dilution matrix: (1) features automatic generation of 20 different measurement
conditions from three input liquids and (2) requires only 2.5 μl of protein solution, which corresponds
to a tenfold reduction in sample volume in comparison to the state of the art. Total hands on time for
preparation of 120 different measurement conditions is less than 5 min. Read-out is performed on disk
within the synchrotron beamline P12 at EMBL Hamburg (PETRA III, DESY). We demonstrate: (1) aliquoting
of 40 nl aliquots for five different liquids typically used in SAXS and (2) confirm fluidic performance of
aliquoting, merging, mixing and read-out from SAXS experiments (2.7–4.4% CV of protein concentration).
We apply the LabDisk for SAXS for basic analysis methods, such as measurement of the radius of gyration,
and advanced analysis methods, such as the ab initio calculation of 3D models. The suitability of the
LabDisk for SAXS for protein structure analysis under different environmental conditions is demonstrated
for glucose isomerase under varying protein and NaCl concentrations. We show that the apparent radius
of gyration of the negatively charged glucose isomerase decreases with increasing protein concentration
at low salt concentration. At high salt concentration the radius of gyration (Rg) does not change with protein
concentrations. Such experiments can be performed by a non-expert, since the LabDisk for SAXS does
not require attachment of tubings or pumps and can be filled with regular pipettes. The new platform has
the potential to introduce routine high-throughput SAXS screening of protein structures with minimal input
volumes to the regular operation of synchrotron beamlines. F. Stumpf, F. Schwemmer, T. Hutzenlaub, D. Baumann, O. Strohmeier, G. Dingemanns, G. Simons, C. Sager, L. Plobner, F. von Stetten, R. Zengerle, D. MarkLabDisk with complete reagent prestorage for
sample-to-answer nucleic acid based detection of
respiratory pathogens verified with influenza A
H3N2 virus 2016 Lab Chip , volume : 16, pages : 199 - 207» show abstract « hide abstract Abstract Portable point-of-care devices for pathogen detection require easy, minimal and user-friendly handling
steps and need to have the same diagnostic performance compared to centralized laboratories. In this
work we present a fully automated sample-to-answer detection of influenza A H3N2 virus in a centrifugal
LabDisk with complete prestorage of reagents. Thus, the initial supply of the sample remains the only manual
handling step. The self-contained LabDisk automates by centrifugal microfluidics all necessary process
chains for PCR-based pathogen detection: pathogen lysis, magnetic bead based nucleic acid extraction,
aliquoting of the eluate into 8 reaction cavities, and real-time reverse transcription polymerase chain reaction
(RT-PCR). Prestored reagents comprise air dried specific primers and fluorescence probes, lyophilized
RT-PCR mastermix and stick-packaged liquid reagents for nucleic acid extraction. Employing two different
release frequencies for the stick-packaged liquid reagents enables on-demand release of highly wetting
extraction buffers, such as sequential release of lysis and binding buffer. Microfluidic process-flow was successful
in 54 out of 55 tested LabDisks. We demonstrate successful detection of the respiratory pathogen
influenza A H3N2 virus in a total of 18 LabDisks with sample concentrations down to 2.39 × 104 viral RNA
copies per ml, which is in the range of clinical relevance. Furthermore, we detected RNA bacteriophage
MS2 acting as internal control in 3 LabDisks with a sample concentration down to 75 plaque forming units
(pfu) per ml. All experiments were applied in a 2 kg portable, laptop controlled point-of-care device. The
turnaround time of the complete analysis from sample-to-answer was less than 3.5 hours. J. Riba, T. Gleichmann, S. Zimmermann, R. Zengerle, P. KoltayLabel-free isolation and deposition
of single bacterial cells from
heterogeneous samples for clonal
culturing 2016 Scientific Reports , volume : 6, page : 32837 » show abstract « hide abstract Abstract The isolation and analysis of single prokaryotic cells down to 1 μm and less in size poses a special
challenge and requires micro-engineered devices to handle volumes in the picoliter to nanoliter range.
Here, an advanced Single-Cell Printer (SCP) was applied for automated and label-free isolation and
deposition of bacterial cells encapsulated in 35 pl droplets by inkjet-like printing. To achieve this,
dispenser chips to generate micro droplets have been fabricated with nozzles 20 μm in size. Further,
the magnification of the optical system used for cell detection was increased. Redesign of the optical
path allows for collision-free addressing of any flat substrate since no compartment protrudes below
the nozzle of the dispenser chip anymore. The improved system allows for deterministic isolation of
individual bacterial cells. A single-cell printing efficiency of 93% was obtained as shown by printing
fluorescent labeled E. coli. A 96-well plate filled with growth medium is inoculated with single bacteria
cells on average within about 8 min. Finally, individual bacterial cells from a heterogeneous sample
of E. coli and E. faecalis were isolated for clonal culturing directly on agar plates in user-defined array
geometry. K. G. Kraiczek, J. Mannion, S. Post, A. Tsupryk, V. Raghunathan, R. Brennen, R. ZengerleMicromachined Fused Silica Liquid Core Waveguide Capillary Flow Cell 2016 Anal Chem , volume : 88, pages : 1100 - 1105» show abstract « hide abstract Abstract A planar, chip-based flow cell for UV−vis absorbance detection
in HPLC is presented. The device features a microfabricated free-standing
liquid core waveguide (LCW) capillary detection tube of long path length that
is based on total internal reflection. We report on the linearity and calibration
slope characteristics of lithographically produced LCWs with different
interior/exterior geometries. 3D ray tracing was indispensable in modeling
behavior in the more demanding geometries: multipath behavior may be
intrinsic to these waveguides with consequent nonlinearity. Fortunately,
nonlinearity in lithographically easy-to-produce waveguide geometries (such as
with a flat, concave exterior and a round interior) is not as detrimental as
might be initially expected. Experimental performance is predictably affected
by the attainable surface quality of the LCW and efficient and reproducible
coupling of the input light into the LCW. J. Riba, N. Renz, C. Niemöller, S. Bleul, D. Pfeifer, J. M. Stosch, K. H. Metzeler, B. Hackanson, M. Lübbert, J. Duyster, P. Koltay, R. Zengerle, R. Claus, S. Zimmermann, H. BeckerMolecular Genetic Characterization of Individual Cancer Cells Isolated via Single-Cell Printing 2016 Plos One , volume : 6, page : 32837» show abstract « hide abstract Abstract Intratumoral genetic heterogeneity may impact disease outcome. Gold standard for dissecting clonal heterogeneity are single-cell analyses. Here, we present an efficient workflow based on an advanced Single-Cell Printer (SCP) device for the study of gene variants in single cancer cells. To allow for precise cell deposition into microwells the SCP was equipped with an automatic dispenser offset compensation, and the 384-microwell plates were electrostatically neutralized. The ejection efficiency was 99.7% for fluorescent beads (n = 2304) and 98.7% for human cells (U-2 OS or Kasumi-1 cancer cell line, acute myeloid leukemia [AML] patient; n = 150). Per fluorescence microscopy, 98.8% of beads were correctly delivered into the wells. A subset of single cells (n = 81) was subjected to whole genome amplification (WGA), which was successful in all cells. On empty droplets, a PCR on LINE1 retrotransposons yielded no product after WGA, verifying the absence of free-floating DNA in SCP-generated droplets. Representative gene variants identified in bulk specimens were sequenced in single-cell WGA DNA. In U-2 OS, 22 of 25 cells yielded results for both an SLC34A2 and TET2 mutation site, including cells harboring the SLC34A2 but not the TET2 mutation. In one cell, the TET2 mutation analysis was inconclusive due to allelic dropout, as assessed via polymorphisms located close to the mutation. Of Kasumi-1, 23 of 33 cells with data on both the KIT and TP53 mutation site harbored both mutations. In the AML patient, 21 of 23 cells were informative for a TP53 polymorphism; the identified alleles matched the loss of chromosome arm 17p. The advanced SCP allows efficient, precise and gentle isolation of individual cells for subsequent WGA and routine PCR/sequencing-based analyses of gene variants. This makes single-cell information readily accessible to a wide range of applications and can provide insights into clonal heterogeneity that were indeterminable solely by analyses of bulk specimens. F. Schuler, M. Trotter, R. Zengerle, F. von StettenMonochrome Multiplexing in Polymerase Chain Reaction by
Photobleaching of Fluorogenic Hydrolysis Probes 2016 Anal Chem , volume : 88, issue : 5, pages : 2590 - 2595» show abstract « hide abstract Abstract Multiplexing in polymerase chain reaction (PCR) is a
technique widely used to save cost and sample material and to increase
sensitivity compared to distributing a sample to several singleplex reactions.
One of the most common methods to detect the different amplification
products is the use of fluorogenic probes that emit at different wavelengths
(colors). To reduce the number of detection channels, several methods for
monochrome multiplexing have been suggested. However, they pose
restrictions to the amplifiable target length, the sequence, or the melting
temperature. To circumvent these limitations, we suggest a novel approach
that uses different fluorophores with the same emission maximum. Discrimination is achieved by their different fluorescence
stability during photobleaching. Atto488 (emitting at the same wavelength as 6-carboxyfluorescein, FAM) and Atto467N
(emitting at the same wavelength as cyanine 5, Cy5) were found to bleach significantly less than FAM and Cy5; i.e., the final
fluorescence of Atto dyes was more than tripled compared to FAM and Cy5. We successfully applied this method by performing
a 4-plex PCR targeting antibiotic resistance genes in S. aureus using only 2 color channels. Confidence of discrimination between
the targets was >99.9% at high copy initial copy numbers of 100 000 copies. Cases where both targets were present could be
discriminated with equal confidence for Cy5 channel and reduced levels of confidence (>68%) for FAM channel. Moreover, a 2-
plex digital PCR reaction in 1 color channel was shown. In the future, the degree of multiplexing may be increased by adding
fluorogenic probe pairs with other emission wavelengths. The method may also be applied to other probe and assay formats, such
as Förster resonance energy transfer (FRET) probes and immunoassays. F. Sun, L. Zielke, H. Markötter, A. Hilger, D. Zhou, R. Moroni, R. Zengerle, S. Thiele, J. Banhart, I. MankeMorphological Evolution of Electrochemically Plated/Stripped Lithium Microstructures
Investigated by Synchrotron X‑ray Phase
Contrast Tomography 2016 Acs Nano , volume : 10, pages : 7990 - 7997» show abstract « hide abstract Abstract Due to its low redox potential and high
theoretical specific capacity, Li metal has drawn worldwide
research attention because of its potential use in nextgeneration
battery technologies such as Li−S and Li−O2.
Unfortunately, uncontrollable growth of Li microstructures
(LmSs, e.g., dendrites, fibers) during electrochemical Li
stripping/plating has prevented their practical commercialization.
Despite various strategies proposed to mitigate LmS
nucleation and/or block its growth, a fundamental understanding
of the underlying evolution mechanisms remains
elusive. Herein, synchrotron in-line phase contrast X-ray
tomography was employed to investigate the morphological
evolution of electrochemically deposited/dissolved LmSs
nondestructively. We present a 3D characterization of
electrochemically stripped Li electrodes with regard to
electrochemically plated LmSs. We clarify fundamentally
the origin of the porous lithium interface growing into Li
electrodes. Moreover, cleavage of the separator caused by
growing LmS was experimentally observed and visualized in
3D. Our systematic investigation provides fundamental
insights into LmS evolution and enables us to understand the evolution mechanisms in Li electrodes more profoundly. R. Moroni, M. Börner, L. Zielke, M. Schroeder, S. Nowak, M. Winter, I. Manke, R. Zengerle, S. ThieleMulti-Scale Correlative Tomography of a Li-Ion Battery Composite Cathode 2016 Sci Rep-uk , volume : 6, page : 30109» show abstract « hide abstract Abstract Focused ion beam/scanning electron microscopy tomography (FIB/SEMt) and synchrotron X-ray
tomography (Xt) are used to investigate the same lithium manganese oxide composite cathode at
the same specific spot. This correlative approach allows the investigation of three central issues in the
tomographic analysis of composite battery electrodes: (i) Validation of state-of-the-art binary active
material (AM) segmentation: Although threshold segmentation by standard algorithms leads to very
good segmentation results, limited Xt resolution results in an AM underestimation of 6 vol% and
severe overestimation of AM connectivity. (ii) Carbon binder domain (CBD) segmentation in Xt data:
While threshold segmentation cannot be applied for this purpose, a suitable classification method is
introduced. Based on correlative tomography, it allows for reliable ternary segmentation of Xt data
into the pore space, CBD, and AM. (iii) Pore space analysis in the micrometer regime: This segmentation
technique is applied to an Xt reconstruction with several hundred microns edge length, thus validating
the segmentation of pores within the micrometer regime for the first time. The analyzed cathode
volume exhibits a bimodal pore size distribution in the ranges between 0–1 μm and 1–12 μm. These
ranges can be attributed to different pore formation mechanisms. S. Wadle, M. Lehnert, S. Rubenwolf, R. Zengerle, F. von StettenReal-time PCR probe optimization using design of experiments approach 2016 Biomolecular Detection and Quantification , volume : 7, pages : 1 - 8» show abstract « hide abstract Abstract Primer and probe sequence designs are among the most critical input factors in real-time polymerase chain reaction (PCR) assay optimization. In this study, we present the use of statistical design of experiments (DOE) approach as a general guideline for probe optimization and more specifically focus on design optimization of label-free hydrolysis probes that are designated as mediator probes (MPs), which are used in reverse transcription MP PCR (RT-MP PCR). The effect of three input factors on assay performance was investigated: distance between primer and mediator probe cleavage site; dimer stability of MP and target sequence (influenza B virus); and dimer stability of the mediator and universal reporter (UR). The results indicated that the latter dimer stability had the greatest influence on assay performance, with RT-MP PCR efficiency increased by up to 10% with changes to this input factor. With an optimal design configuration, a detection limit of 3–14 target copies/10 μl reaction could be achieved. This improved detection limit was confirmed for another UR design and for a second target sequence, human metapneumovirus, with 7–11 copies/10 μl reaction detected in an optimum case. The DOE approach for improving oligonucleotide designs for real-time PCR not only produces excellent results but may also reduce the number of experiments that need to be performed, thus reducing costs and experimental times. S. Burger, M. Schulz, F. von Stetten, R. Zengerle, N. PaustRigorous buoyancy driven bubble mixing for centrifugal microfluidics 2016 Lab Chip , pages : 261 - 268» show abstract « hide abstract Abstract We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations. L. Gutzweiler, F. Stumpf, L. Tanguy, G. Roth, P. Koltay, R. Zengerle, L. RieggerSemi-contact-writing of polymer molds for prototyping PDMS chips with low surface roughness, sharp edges and locally varying channel heights 2016 J Micromech Microeng , volume : 26, issue : 4, pages : 45018 - 45027» show abstract « hide abstract Abstract Microfluidic systems fabricated in polydimethylsiloxane (PDMS) enable a broad variety of applications and are widespread in the field of Lab-on-a-Chip. Here we demonstrate semi-contact-writing, a novel method for fabrication of polymer based molds for casting microfluidic PDMS chips in a highly flexible, time and cost-efficient manner. The method is related to direct-writing of an aqueous polymer solution on a planar glass substrate and substitutes conventional, time- and cost-consuming UV-lithography. This technique facilitates on-demand prototyping in a low-cost manner and is therefore ideally suited for rapid chip layout iterations. No cleanroom facilities and less expertise are required. Fabrication time from scratch to ready-to-use PDMS-chip is less than 5 h. This polymer writing method enables structure widths down to 140 μm and controllable structure heights ranging from 5.5 μm for writing single layers up to 98 μm by stacking. As a unique property, freely selectable height variations across a substrate can be achieved by application of local stacking. Furthermore, the molds exhibit low surface roughness (R a = 24 nm, R RMS = 28 nm) and high fidelity edge sharpness. We validated the method by fabrication of molds to cast PDMS chips for droplet based flow-through PCR with single-cell sensitivity. S. Wadle, M. Lehnert, F. Schuler, R. Köppel, A. Serr, R. Zengerle, F. von StettenSimplified development of multiplex real-time PCR
through master mix augmented by universal
fluorogenic reporters 2016 BioTechniques , volume : 61, pages : 123 - 128» show abstract « hide abstract Abstract Mediator probe (MP) PCR is a real-time PCR approach that uses standardized universal fluorogenic reporter
oligonucleotides (UR) in conjunction with label-free sequence-specific probes. To enable multiplex
real-time MP PCR, we designed a set of five optimized URs with different fluorescent labels. Performance
of the optimized URs was verified in multiplex real-time MP PCR for the detection of a pentaplex food
panel and a quadruplex methicillin-resistant Staphylococcus aureus (MRSA) panel. Results were comparable
to corresponding multiplex hydrolysis probe (HP) PCR, also designated as TaqMan PCR. Analyses
of MRSA DNA standards and DNA extracted from patient swab samples showed improved lower limits
of detection (LoDs) by a factor of 2–5 when using quadruplex real-time MP PCR instead of HP PCR. The
novel set of standardized URs we present here simplifies development of multiplex real-time PCR assays
by requiring only the design of label-free probes. In the future, real-time PCR master mixes could be
augmented with up to five standardized fluorogenic URs, each emitting light at a different wavelength. S. Kartmann, F. Koch, P. Koltay, R. Zengerle, A. ErnstSingle-use capacitive pressure sensor employing radial expansion of a silicone tube 2016 Sensor Actuat A-phys , volume : 247» show abstract « hide abstract Abstract This paper reports on a single-use pressure sensor for medical applications. The sensor principle
makes use of the radial expansion of a silicone tube which occurs when there is a pressure
difference between the inside and the outside of the tube. The change in outer diameter is
detected by a capacitive measurement method, whereas the amplification electronics can be
separated from the tube being in contact with the fluid. This enables a cross-contamination-free
measurement system for patient near application as e.g. within infusion systems. The sensor
includes a novel highly sensitive and fast analog amplification circuit in combination with gold
electrodes fabricated in PCB technology. This circuit enables to amplify even highly dynamic
pressure changes, in the range of a few milliseconds causing capacitive changes on the electrodes
in the fF range to a readable voltage level. A functional model is developed based on flex board
technology which allows for studying the influence of the electrode geometry as well as the
material properties of the silicone tube with respect to the sensitivity of the sensor. The best
performing electrode geometry determined by experiments features a sensitivity of 0.195 fF/kPa
at a mean coefficient of variation (CV) of 6.4%, considering three individual sensor assemblies.
A sensor prototype is designed and fabricated based on the results of the investigated functional
model. The performance of the prototype is investigated experimentally in a pressure range from
0 to 40 kPa. As a result a sensitivity of 0.135 V/kPa for DI water as measurement liquid could be
achieved and a good linearity of the signal (R² = 0.996) was observed up to 35 kPa. L. Zielke, F. Sun, H. Markötter, A. Hilger, R. Moroni, R. Zengerle, S. Thiele, J. Banhart, I. MankeSynchrotron X-ray tomographic study of a silicon electrode before and after discharge and the effect of cavities on particle fracturing 2016 Chemelectrochem , volume : 3, pages : 1170 - 1177» show abstract « hide abstract Abstract Silicon (Si) has been proposed as one of the most
promising anode materials for next-generation lithium ion batter-
ies, but unsatisfactory discharge capacity and inevitable perfor-
mance deterioration prevent their commercialization. We apply
in situ synchrotron X-ray tomography to a Si-composite elec-
trode in its pristine and firstly discharged state and quantitatively
investigate degradation of the electron- and/or ion- conducting
network as well as degradation of Si particles. Thus this study is
complementary to previous X-ray tomographic studies focusing
on the Si particles only. We found that on the electrode level the
Si particles located in the central part of the electrode primarily
experience crack formation; on the particle level, lithiation be-
haviour is heterogeneous and cavities are formed during elec-
trode preparation and battery operation. The correlation between
the electrochemical activities of Si particles and their individual
contact with the conducting network is investigated and quanti-
fied: Si particles will experience lithiation only under the condi-
tion that at least 40% of their surface is electrically and ionically
connected. I. Schwarz, S. Zehnle, T. Hutzenlaub, R. Zengerle, N. PaustSystem-level network simulation for robust centrifugal-microfluidic lab-on-a-chip systems 2016 Lab Chip , volume : 16, pages : 1873 - 1885» show abstract « hide abstract Abstract Centrifugal microfluidics shows a clear trend towards a higher degree of integration and parallelization1. This trend leads to an increase in number and density of integrated microfluidic unit operations. The fact that all unit operations are processed by the same common spin protocol turns higher integration into higher complexity. To allow for efficient development anyhow, we introduce advanced lumped models for network simulations in centrifugal microfluidics. These models consider the interplay of centrifugal and Euler pressures, viscous dissipation, capillary pressures and pneumatic pressures. The simulations are fast and simple to set up and allow for the precise prediction of flow rates as well as switching and valving events. During development, channel and chamber geometry variations due to manufacturing tolerances can be taken into account as well as pipetting errors, variations of contact angles, compliant chamber walls and temperature variations in the processing device. As an example for considering these parameters during development, we demonstrate simulation based robustness analysis for pneumatic siphon valving in centrifugal microfluidics. Subsequently the influence of liquid properties on pumping and valving is studied for four liquids relevant for biochemical analysis, namely: water (large surface tension), blood plasma (large contact angle hysteresis), ethanol/water (highly wetting) and glycerine/water (highly viscous). In a second example, we derive a spin protocol to attain a constant flow rate under varying pressure conditions. Both examples show excellent agreement to experimental validations. J. Madjarov, A. Prokhorova, T. Messinger, J. Gescher, S. KerzenmacherThe performance of microbial anodes in municipal wastewater: Pre-grown multispecies biofilm vs. natural inocula 2016 Bioresour Technol. , volume : 221, pages : 165 - 171» show abstract « hide abstract Abstract In this study, different inoculation strategies for continuously operated microbial anodes are analyzed and compared. After 20 days of operation with municipal wastewater anodes pre-incubated with a biofilm of the exoelectrogenic species Geobacter and Shewanella showed current densities of (65 ± 8) μA/cm2. This is comparable to the current densities of non-inoculated anodes and anodes inoculated with sewage sludge. Analysis of the barcoded pre-grown multispecies biofilms reveal that 99% of the original biofilm was detached after 20 days of operation with municipal wastewater. This is in contrast to previous experiments where a pre-grown biofilm of exoelectrogens was operated in batch mode. To implement pre-grown biofilms in continuous systems it will thus be necessary to reveal a window of process parameters in which typical exoelectrogenic microorganisms including model organisms can be kept and/or enriched on anodes. S. Vierrath, M. Breitwieser, M. Klingele, B. Britton, S. Holdcroft, R. Zengerle, S. ThieleThe reasons for the high power density of fuel cells fabricated with directly deposited membranes 2016 J. of Power Sources , volume : 326, pages : 170 - 175» show abstract « hide abstract Abstract In a previous study, we reported that polymer electrolyte fuel cells prepared by direct membrane
deposition (DMD) produced power densities in excess of 4 W/cm2. In this study, the underlying origins
that give rise to these high power densities are investigated and reported. The membranes of high power,
DMD-fabricated fuel cells are relatively thin (12 mm) compared to typical benchmark, commercially
available membranes. Electrochemical impedance spectroscopy, at high current densities (2.2 A/cm2)
reveals that mass transport resistance was half that of reference, catalyst-coated-membranes (CCM). This
is attributed to an improved oxygen supply in the cathode catalyst layer by way of a reduced propensity
of flooding, and which is facilitated by an enhancement in the back diffusion of water from cathode to
anode through the thin directly deposited membrane. DMD-fabricated membrane-electrode-assemblies
possess 50% reduction in ionic resistance (15 mUcm2) compared to conventional CCMs, with contributions
of 9 mUcm2 for the membrane resistance and 6 mUcm2 for the contact resistance of the membrane
and catalyst layer ionomer. The improved mass transport is responsible for 90% of the increase in power
density of the DMD fuel cell, while the reduced ionic resistance accounts for a 10% of the improvement. L. Zielke, S. Vierrath, R. Moroni, A. Mondon, R. Zengerle, S. ThieleThree-dimensional Morphology of the Interface
between Micro Porous Layer and Catalyst Layer in a
Polymer Electrolyte Membrane Fuel Cell 2016 Rsc Advances , volume : 6, pages : 80700 - 80705» show abstract « hide abstract Abstract Interfaces between the different layers in proton exchange membrane fuel cells are expected to
influence transport properties and therefore cell performance. So far the interface between
micro porous layer (MPL) and catalyst layer (CL) was difficult to investigate due to its nanometer
scale morphology. We apply focused ion beam scanning electron microscopy tomography with
pore contrasting via atomic layer deposition to reconstruct a representative volume of 5.1 μm x
1.5 μm x 4.5 μm containing CL, MPL and their interface. We find that platinum in the CL results
in brighter SEM image intensities, compared to the MPL. This allows i) estimating the extension
of the interfacial region (530 nm), ii) evaluating Pt-content homogeneity in the CL and iii)
calculating the individual roughnesses for the CL (102 nm) and for the MPL (129 nm). We
further calculate porosity, pore sizes, and oxygen diffusivities. Thus, we find that the values of
the parameters of the interfacial region are between those of the CL and the MPL, meaning that
on the investigated scale, the interface is a homogeneous transitional region. A
representativeness analysis shows that our reconstructed volume is sufficiently large
concerning all calculated parameters. M. Breitwieser, R. Moroni, J. Schock, M. Schulz, B. Schillinger, F. Pfeiffer, R. Zengerle, S. ThieleWater management in novel direct membrane
deposition fuel cells under low humidification 2016 Int J Hydrog Energ , volume : 41, pages : 11412 - 11417» show abstract « hide abstract Abstract Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane deposition
(DMD) were shown to work even at dry conditions without significant deterioration of
the membrane resistance. Here, in situ neutron radiography is used to investigate the
water management in those fuel cells to uncover the phenomena that lead to the robust
operation under low humidification. A constant level of humidification within the membrane
electrode assembly (MEA) of a DMD fuel cell is observed even under dry anode
operation and 15% relative humidity on the cathode side. This proves a pronounced back
diffusion of generated water from the cathode side to the anode side through the thin
deposited membrane layer. Over the entire range of polarization curves a very high similarity
of the water evolution in anode and cathode flow fields is found in spite of different
humidification levels. It is shown that the power density of directly deposited membranes
in contrast to a 50 mm thick N-112 membrane is only marginally affected by dry operation
conditions. Water profiles in through-plane direction of the MEA reveal that the water
content in the DMD fuel cell remains steady even at high current densities. This is in
contrast to the N-112 reference fuel cell which shows a strong increase in membrane
resistance and a reduced MEA water content with raising current densities. Thus this new
MEA fabrication technique has a promising perspective, since dry operation conditions are
highly requested in order to reduce fuel cell system costs. back to the year overview S. Kartmann, P. Koltay, R. Zengerle, A. ErnstA Disposable Dispensing Valve for Non-Contact Microliter Applications in a 96-Well Plate Format 2015 Micromachines , volume : 6, pages : 423 - 436» show abstract « hide abstract Abstract We present a miniaturized, disposable, normally-closed electromagnetic dispensing valve for the microliter range to process 96-well plates. The novel injection-molded valve is designed to fit into a 9 mm grid to realize an eight channel dispensing head, enabling the serial processing of well plates row-by-row. The presented dispensing valve design originates from a miniaturization study of a previously developed functional model. The outer diameter of the valve, including all actuating components, was reduced by 8 mm to an overall diameter of 8.5 mm without compromising the performance. Additionally, the actuation current of the valve could be reduced to 5 A. The valve is characterized for a volume range between 840 nL and 5.3 μL. The performance of the injection molded valve is competitive to commercially available dispensing valves, featuring the advantages of low fabrication costs, disposability, low mounting size, easy handling, and super silent actuation. D. Czurratis, Y. Beyl, S. Zinober, F. Lärmer, R. ZengerleA novel concept for long-term pre-storage
and release of liquids for pressure-driven
lab-on-a-chip devices 2015 J Micromech Microeng , volume : 25, page : 045002» show abstract « hide abstract Abstract On-chip storage of liquids is one of the major challenges of polymer-based lab-on-a-chip
(LoC) devices. To ensure long-term storage of even highly volatile reagents in polymer
disposal LoC cartridges, robust reagent storage concepts are necessary. Tubular bags, so-called
stick packs, are widely used in the packaging industry. They offer sufficient vapor barrier
properties for liquid storage. Here we present a polymer multilayer LoC-stack with integrated
stick packs for the long-term storage of liquid reagents required for diagnostic applications.
The storage concept fulfils two main requirements: firstly, the long-term storage of reagents
in stick packs without significant losses or interaction with the surroundings and secondly,
the on-demand release of liquids, which is realized by the delamination of a stick pack’s
peel seam through pneumatic pressure. Furthermore, effects on the opening behavior of stick
packs through accelerated aging were investigated after different storage conditions to proof
repeatability. This concept enables on-chip storage of liquid reagents at room temperature and
allows the implementation in different pressure driven LoC devices or similar applications.
Since liquid storage in stick packs is well-established, emerging fields such as lab-on-achip
combined with novel reagent release mechanisms should be of great interest for the
commercialization of life science products. S.K. Vashist, T. van Oordt, E. M. Schneider, R. Zengerle, F. von Stetten, J.H.T. LuongA smartphone-based colorimetric reader for bioanalytical applications using the screen-based bottom illumination provided by gadgets 2015 Biosens Bioelectron , volume : 67, pages : 248 - 255» show abstract « hide abstract Abstract A smartphone-based colorimetric reader (SBCR) was developed using a Samsung Galaxy SIII mini, a gadget (iPAD mini, iPAD4 or iPhone 5s), integrated with a custom-made dark hood and base holder assembly. The smartphone equipped with a back camera (5 megapixels resolution) was used for colorimetric imaging via the hood and base-holder assembly. A 96- or 24-well microtiter plate (MTP) was positioned on the gadget's screensaver that provides white light-based bottom illumination only in the specific regions corresponding to the bottom of MTP's wells. The pixel intensity of the captured images was determined by an image processing algorithm. The developed SBCR was evaluated and compared with a commercial MTP reader (MTPR) for three model assays: our recently developed human C-reactive protein sandwich enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase direct ELISA, and bicinchoninic acid protein estimation assay. SBCR had the same precision, dynamic range, detection limit and sensitivity as MTPR for all three assays. With advanced microfabrication and data processing, SBCR will become more compact, lighter, inexpensive and enriched with more features. Therefore, SBCR with a remarkable computing power could be an ideal point-of-care (POC) colorimetric detection device for the next-generation of cost-effective POC diagnostics, immunoassays and diversified bioanalytical applications. M. Blazek, T. Silva Santisteban, R. Zengerle, M. MeierAnalysis of fast protein phosphorylation kinetics in single cells on a microfluidic chip 2015 Lab Chip , volume : 15, pages : 726 - 734» show abstract « hide abstract Abstract In the present study, we developed a microfluidic large-scale integration (mLSI) platform for the temporal and chemical control of cell cultures to study fast kinetics of protein phosphorylation. For in situ protein analysis the mLSI chip integrates the Proximity Ligation Assay (PLA). To investigate cell-signaling events with a time resolution of a few seconds we first engineered and optimized the fluidic layout of the chip with 128 individual addressable cell culture chambers. The functionality of the cell culture operations and PLA is demonstrated by the determination of the minimum cell sample size for obtaining robust quantitative PLA signals at the single-cell level. We show that at least 350 cells per assay condition are required to statistically evaluate single cell PLA data. In the following we used the PLA chip with over 500 hundred cells per condition to record sequential phosphorylation reactions of the canonical protein kinase within the Akt pathway, which is activated in various human cancer types. This was achieved by stimulating mouse fibroblast cell cultures with either the platelet-derived growth factor (PDGF) or insulin-like growth factor (IGF-1). Fluidic cell stimulation pulses of 5 seconds were followed by precisely time shifted cell fixation pulses to obtain a temporal resolution of 10 seconds. PLA was then performed on all fixed arrays of cell cultures to extract the characteristic phosphorylation times at the single cell level for either the PDGF, or IGF-1 receptor and the Akt and GSK3 beta kinases. Characteristic phosphorylation times for the receptors were between 13 and 35 seconds, whereas for downstream kinases between 25 and 200 seconds. Thus we could reveal a molecular order of the phosphorylation reactions during the signal transduction through the Akt pathway. In dependence of the stimulus we found a temporal difference for the characteristic phosphorylation time of 20 and 150 seconds for the Ser-473 and Thr-308 residues on the Akt kinase, respectively. Temporal alteration of sequential phosphorylation reactions on Akt has been proposed as molecular mechanism to differentiate between stimuli and biophysically determined in the present study. M. Keller, J. Naue, R. Zengerle, F. von Stetten, U. SchmidtAutomated Forensic Animal Family Identification by Nested PCR and Melt Curve Analysis on an Off-the-Shelf Thermocycler Augmented with a Centrifugal Microfluidic Disk Segment 2015 Plos One , volume : 10, issue : 7, page : e0131845» show abstract « hide abstract Abstract Nested PCR remains a labor-intensive and error-prone biomolecular analysis. Laboratory workflow automation by precise control of minute liquid volumes in centrifugal microfluidic Lab-on-a-Chip systems holds great potential for such applications. However, the majority of these systems require costly custom-made processing devices. Our idea is to augment a standard laboratory device, here a centrifugal real-time PCR thermocycler, with inbuilt liquid handling capabilities for automation. We have developed a microfluidic disk segment enabling an automated nested real-time PCR assay for identification of common European animal groups adapted to forensic standards. For the first time we utilize a novel combination of fluidic elements, including pre-storage of reagents, to automate the assay at constant rotational frequency of an off-the-shelf thermocycler. It provides a universal duplex pre-amplification of short fragments of the mitochondrial 12S rRNA and cytochrome b genes, animal-group-specific main-amplifications, and melting curve analysis for differentiation. The system was characterized with respect to assay sensitivity, specificity, risk of cross-contamination, and detection of minor components in mixtures. 92.2% of the performed tests were recognized as fluidically failure-free sample handling and used for evaluation. Altogether, augmentation of the standard real-time thermocycler with a self-contained centrifugal microfluidic disk segment resulted in an accelerated and automated analysis reducing hands-on time, and circumventing the risk of contamination associated with regular nested PCR protocols. O. Strohmeier, S. Keil, B. Kanat, P. Patel, M. Niedrig, M. Weidmann, F. Hufert, J. Drexler, R. Zengerle, F. von StettenAutomated nucleic acid extraction from whole blood, B . subtilis, E. coli, and Rift Valley fever virus on a centrifugal microfluidic LabDisk 2015 Rsc Adv , volume : 5, page : 32144» show abstract « hide abstract Abstract We present total nucleic acid extraction from whole blood, Gram‐positive Bacillus subtilis, Gram‐negative Escherichia coli,
and Rift Valley fever RNA virus on a low‐cost, centrifugal microfluidic LabDisk cartridge processed in a light‐weight (< 2 kg)
and portable processing device. Compared to earlier work in disk based centrifugal microfluidics, this includes the
following advances: combined lysis and nucleic acid purification on one cartridge and handling of sample volumes as large
as 200 μL. The presented system has been validated for logarithmic dilutions of aforementioned bacteria and viruses from
various sample matrices including blood plasma and culture media and extraction of human DNA from whole blood.
Recovered DNA and RNA concentrations in the eluate were characterized by quantitative PCR to: 58.2 % ‐ 98.5 %, 45.3 % ‐
102.1 % and 29.5 % ‐ 34.2 % versus manual reference for Bacillus subtilis, Escherichia coli and Rift Valley fever virus,
respectively. For extraction of human DNA from whole blood, similar results for on‐disk ((10.1 ± 7.6) x 104 DNA copies) and
manual reference extraction ((10.2 ± 6.3) x 104 DNA copies)) could be achieved. Eluates from on‐disk extraction show
slightly increased ethanol concentrations of 4.1 ± 0.3 % to 5.5 ± 0.2 % compared to manual reference (2.0 ± 0.5 % to 3.6 ±
0.6 %). The complete process chain for sample preparation is automatically performed within ~30 minutes, including ~15
minutes lysis time. It is amenable to concatenation with downstream modules for multiplex nucleic acid amplification as
recently demonstrated for panel testing of various pathogens at the point of care. F. Schuler, N. Paust, R. Zengerle, F. von StettenCentrifugal Step Emulsification can Produce Water in Oil Emulsions with Extremely High Internal Volume Fractions 2015 Micromachines , volume : 6, issue : 8, pages : 1180 - 1188» show abstract « hide abstract Abstract The high throughput preparation of emulsions with high internal volume fractions is important for many different applications, e.g., drug delivery. However, most emulsification techniques reach only low internal volume fractions and need stable flow rates that are often difficult to control. Here, we present a centrifugal high throughput step emulsification disk for the fast and easy production of emulsions with high internal volume fractions above 95%. The disk produces droplets at generation rates of up to 3700 droplets/s and, for the first time, enables the generation of emulsions with internal volume fractions of >97%. The coefficient of variation between droplet sizes is very good (4%). We apply our system to show the in situ generation of gel emulsion. In the future, the recently introduced unit operation of centrifugal step emulsification may be used for the high throughput production of droplets as reaction compartments for clinical diagnostics or as starting material for micromaterial synthesis. F. Schuler, F. Schwemmer, M. Trotter, S. Wadle, R. Zengerle, F. von Stetten, N. PaustCentrifugal step emulsification applied for absolute
quantification of nucleic acids by digital droplet RPA 2015 Lab Chip , volume : 15, pages : 2759 - 2766» show abstract « hide abstract Abstract Aqueous microdroplets provide miniaturized reaction compartments for numerous chemical,
biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for
the fast and easy production of monodispers droplets. Homogenous droplets with preselectable
diameters in a range from 120 μm to 170 μm were generated with coefficients of
variation of 2-4% and zero run-in time or dead volume. The droplet diameter depends on the
nozzle geometry (depth, width, and step size) and interfacial tensions, only. Droplet size is
demonstrated to be independent of the dispersed phase flow rate between 0.01-1 μl/s, proving
the robustness of the centrifugal approach. Centrifugal step emulsification can easily be
combined with existing centrifugal microfluidic unit operations, is compatible to scalable
manufacturing technologies such as thermoforming or injection moulding and enables fast
emulsification (> 500 droplets per second and nozzle) with minimal handling effort (2-3
pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first
digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute
quantification of Listerias monocytogenes DNA concentration standards with a total analysis
time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with
processing times of about 2 hours, the overall processing time of digital analysis was reduced
by more than a factor of 4. F. Schwemmer, T. Hutzenlaub, D. Buselmeier, N. Paust, F. von Stetten, D. Mark, R. Zengerle, D. KosseCentrifugo-pneumatic multi-liquid aliquoting – parallel aliquoting and combination of multiple liquids in centrifugal microfluidics 2015 Lab Chip , volume : 15, pages : 3250 - 3258» show abstract « hide abstract Abstract The generation of mixtures with precisely metered volumes is essential for reproducible automation of laboratory workflows. Splitting a given liquid into well-defined metered sub-volumes, the so-called aliquoting, has been frequently demonstrated on centrifugal microfluidics. However, so far no solution exists for assays that require simultaneous aliquoting of multiple, different liquids and the subsequent pairwise combination of aliquots with full fluidic separation before combination. Here, we introduce the centrifugo-pneumatic multi-liquid aliquoting designed for parallel aliquoting and pairwise combination of multiple liquids. All pumping and aliquoting steps are based on a combination of centrifugal forces and pneumatic forces. The pneumatic forces are thereby provided intrinsically by centrifugal transport of the assay liquids into dead end chambers to compress the enclosed air. As an example, we demonstrate simultaneous aliquoting of 1.) a common assay reagent into twenty 5 µl aliquots and 2.) five different sample liquids, each into four aliquots of 5 µl. Subsequently, the reagent and sample aliquots are simultaneously transported and combined into twenty collection chambers. All coefficients of variation for metered volumes were between 0.4% - 1.0% for intra-run variations and 0.5% - 1.2% for inter-run variations. The aliquoting structure is compatible to common assay reagents with a wide range of liquid and material properties, demonstrated here for contact angles between 20° and 60°, densities between 789 and 1855 kg / m3 and viscosities between 0.89 and 4.1 mPa s. The centrifugo-pneumatic multi-liquid aliquoting is implemented as a passive fluidic structure into a single fluidic layer. Fabrication is compatible to scalable fabrication technologies such as injection molding or thermoforming and does not require any additional fabrication steps such as hydrophilic or hydrophobic coatings or integration of active valves. Y. Zhao, F. Schwemmer, S. Zehnle, F. von Stetten, R. Zengerle, N. PaustCentrifugo-pneumatic sedimentation, re-suspension and transport of microparticles 2015 Lab Chip , pages : 4133 - 4137» show abstract « hide abstract Abstract Microparticles are widely used as solid phase for affinity based separation. Here, we introduce a new method for automated handling of microparticles in centrifugal microfluidics that is not restricted by the particle size and requires neither auxiliary means such as magnets nor coating of microfluidic structures. All steps are initiated and controlled by the speed of rotation, only. It is based on storage and “on demand” release of pneumatic energy within tuneable time frames: A slow release of the pneumatic energy triggers a first fluidic path through which the supernatant above the sedimented particles is removed. An abrupt release triggers a second path which allows for liquid routing and transport of the re-suspended particles. Re-suspension of particles is thereby achieved by quickly changing the speed of rotation. We demonstrate the exchange of the particle carrier medium with supernatant removal efficiency of more than 99.5% and particle loss below 4%. Re-suspension and subsequent transport of suspended particles shows particle loss below 7%. The method targets for the automation of particle based assays e.g. DNA extractions and immunoassays. It is compatible to monolithic integration and suitable for mass production technologies e.g. thermoforming or injection moulding. M. Keller, S. Wadle, N. Paust, L. Dreesen, C. Nuese, O. Strohmeier, R. Zengerle, F. von StettenCentrifugo-thermopneumatic fluid control for valving and aliquoting applied to multiplex real-time PCR on off-the-shelf centrifugal thermocycler 2015 Rsc Adv , volume : 5, pages : 89603 - 89611» show abstract « hide abstract Abstract We introduce microfluidic automation of geometrically multiplexed real-time PCR to off-the-shelf Rotor-Gene Q thermocyclers (RGQ, QIAGEN GmbH, Hilden, Germany). For centrifugal fluid control the RGQ provides low and constant rotation of 400 rpm, only. Compatibility to this very limited flexibility of centrifugal actuation is achieved by using thermal gas compression and expansion for valving and aliquoting. In contrast to existing thermo-pneumatic actuation, centrifugo-thermopneumatic (CTP) fluid control employs the induced change of partial vapor pressure by global temperature control as actuation parameter for two new unit operations: CTP siphon valving and CTP two-stage aliquoting. CTP siphon valving was demonstrated to reliably transfer sample liquid in all cases (n = 35) and CTP two-step aliquoting transfers metered aliquots of 18.2 ± 1.2 μl (CV 6.7%, n = 8) into reaction cavities within 5 s (n = 24). Thermal characteristics of CTP two-stage aliquoting were found to be in good agreement with an introduced analytical model (R2 = 0.9876, n = 3). A microfluidic disk segment comprising both new unit operations was used for automation of real-time PCR amplification of Escherichia coli DNA. Required primers and probes were pre-stored in the reaction cavities and a comparison with reference reactions in conventional PCR tubes yielded the same PCR efficiency, repeatability, and reproducibility. L. Zielke, C. Barchasz, S. Waluś, F. Alloin, J.-C. Leprêtre, A. Spettl, V. Schmidt, A. Hilger, I. Manke, J. Banhart, R. Zengerle, S. ThieleDegradation of Li/S Battery Electrodes On 3D Current Collectors Studied Using X-ray Phase Contrast Tomography 2015 Sci Rep-uk , volume : 5, page : 10921» show abstract « hide abstract Abstract Lithium/sulphur batteries are promising candidates for future energy storage systems, mainly
due to their high potential capacity. However low sulphur utilization and capacity fading hinder
practical realizations. In order to improve understanding of the system, we investigate Li/S electrode
morphology changes for different ageing steps, using X-ray phase contrast tomography. Thereby
we find a strong decrease of sulphur loading after the first cycle, and a constant loading of about
15% of the initial loading afterwards. While cycling, the mean sulphur particle diameters decrease
in a qualitatively similar fashion as the discharge capacity fades. The particles spread, migrate into
the current collector and accumulate in the upper part again. Simultaneously sulphur particles lose
contact area with the conducting network but regain it after ten cycles because their decreasing size
results in higher surface areas. Since the capacity still decreases, this regain could be associated with
effects such as surface area passivation and increasing charge transfer resistance. M. Klingele, M. Breitwieser, R. Zengerle, S. ThieleDirect Deposition of Proton Exchange Membranes Enabling High Performance Hydrogen Fuel Cells 2015 J. Mat. Chem. A , volume : 3, pages : 11239 - 11245» show abstract « hide abstract Abstract We apply drop-on-demand inkjet printing to fabricate proton exchange membranes for polymer electrolyte fuel cells. This completely substitutes the commonly used membrane foil. A Nafion® dispersion is deposited directly onto the catalyst layers of anode and cathode gas diffusion electrodes, and the two electrodes are pressed together with membrane layers facing each other. Fuel cells constructed utilizing this method reveal a thin overall membrane thickness of 8-25 µm and a good adhesion of membrane and catalyst layers. This results in a membrane ionic resistance of only 12.7 mΩ*cm² without compromising hydrogen crossover, which was determined to be less than 2 mA/cm². We achieve a cell power density exceeding 4 W/cm² with pure oxygen as cathode fuel, which, to our knowledge, is the highest reported power density with a Nafion® membrane hydrogen fuel cell. The membrane shows a stable performance over the entire range of reactant gas humidification from 0 to 100 % relative humidity. Power densities exceeding 1.0 W/cm² are achieved under dry operation with air as cathode fuel. A 576 hour combined mechanical and chemical accelerated stress test reveals no significant degradation of hydrogen crossover, indicating a promising lifetime of the membrane. L. Drechsel, M. Schulz, F. von Stetten, C. Moldovanc, R. Zengerle, N. PaustElectrochemical pesticide detection with AutoDip – a portable platform for automation of crude sample analyses 2015 Lab Chip , volume : 15, pages : 704 - 710» show abstract « hide abstract Abstract Lab-on-a-chip devices hold promise for automation of complex workflows from sample to answer with minimal consumption of reagents in portable devices. However, complex, inhomogeneous samples as they occur in environmental or food analysis may block microchannels and thus often cause malfunction of the system. Here we present the novel AutoDip platform which is based on the movement of a solid phase through the reagents and sample instead of transporting a sequence of reagents through a fixed solid phase. A ball-pen mechanism operated by an external actuator automates unit operations such as incubation and washing by consecutively dipping the solid phase into the corresponding liquids. The platform is applied to electrochemical detection of organophosphorus pesticides in real food samples using an acetylcholinesterase (AChE) biosensor. Minimal sample preparation and an integrated reagent pre-storage module hold promise for easy handling of the assay. Detection of the pesticide chlorpyrifos-oxon (CPO) spiked into apple samples at concentrations of 10−7 M has been demonstrated. This concentration is below the maximum residue level for chlorpyrifos in apples defined by the European Commission. I. Leibacher, J. Schoendube, J. Dual, R. Zengerle, P. KoltayEnhanced single-cell printing by acoustophoretic cell
focusing 2015 Biomicrofluidics , volume : 9, page : 024109» show abstract « hide abstract Abstract Recent years have witnessed a strong trend towards analysis of single-cells. To
access and handle single-cells, many new tools are needed and have partly been
developed. Here, we present an improved version of a single-cell printer which is
able to deliver individual single cells and beads encapsulated in free-flying picoliter
droplets at a single-bead efficiency of 96% and with a throughput of more than 10
beads per minute. By integration of acoustophoretic focusing, the cells could be
focused in x and y direction. This way, the cells were lined-up in front of a 40 µm
nozzle, where they were analyzed individually by an optical system prior to printing.
In agreement with acoustic simulations, the focusing of 10 µm beads and Raji
cells has been achieved with an efficiency of 99% (beads) and 86% (Raji cells) to a
40 µm wide center region in the 1mm wide microfluidic channel. This enabled
improved optical analysis and reduced bead losses. The loss of beads that ended up
in the waste (because printing them as single beads arrangements could not be
ensured) was reduced from 52 ± 6% to 28 ± 1%. The piezoelectric transducer
employed for cell focusing could be positioned on an outer part of the device,
which proves the acoustophoretic focusing to be versatile and adaptable. S. Vierrath, F. Güder, A. Menzel, M. Hagner, R. Zengerle, M. Zacharias, S. ThieleEnhancing the Quality of the Tomography of Nanoporous Materials for Better Understanding of Polymer Electrolyte Fuel Cell Materials 2015 J Power Sources , pages : 413 - 417» show abstract « hide abstract Abstract To investigate the nanostructure of polymer electrolyte fuel cell catalyst layers, focused ion beam - scanning electron microscopy (FIB-SEM) tomography is a common technique. However, as FIB-SEM tomography lacks of image contrast between the catalyst layer and its pores, state-of-the-art reconstruction methods by threshold cannot accurately distinguish between these two phases. We show that this inability leads to an underestimation of the porosity by a factor of nearly two, a reconstruction with channel-like artifacts and that these artifacts make it impossible to calculate reliable diffusivities. To overcome this problem, we fill the pores of the catalyst layer with ZnO via atomic layer deposition prior to tomography. By using atomic layer deposition, even smallest pores can be filled with ZnO, which exhibits a good contrast to the catalyst layer in SEM images. As a result, we present the porosity of the catalyst layer (65%) and its three-dimensional representation without typical reconstruction artifacts. Calculated O2 diffusivities (23.05 - 25.40 x 10-7 m2s-1) inside the catalyst layer are in good agreement with experimental values from the literature. Furthermore, filling with ZnO permits the identification of large Pt clusters inside the catalyst layer, which were estimated to reduce the catalyst surface area by 9%. A.G. Venkatesh, S. K. Vashist, E. M. Schneider, R. Zengerle, F. von Stetten, J. H.T. LuongGraphene-based C-reactive protein immunoassay with smartphone readout 2015 Protocol Exchange » show abstract « hide abstract Abstract A highly-sensitive immunoassay (IA) procedure with minimal process steps has been developed for the detection of human C-reactive protein (CRP) in less than 30 min. Graphene nanoplatelets (GNP) was admixed with 3-aminopropyltriethoxysilane (APTES) and EDC-activated anti-human CRP antibody (Ab) to form a stable complex that was then covalently attached to a KOH-pretreated polystyrene microtiter plate (MTP). The developed one-step kinetics-based IA involves the formation of a sandwich immune complex followed by two washings and an enzyme-based colorimetric reaction that was read by a smartphone-based colorimetric reader (SBCR). The detection range of CRP was 0.03-81 ng mL-1 with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.07 ng mL-1 and 0.9 ng mL-1, respectively. Moreover, the developed IA enabled the detection of CRP spiked in diluted human whole blood and plasma as well as CRP present in clinical plasma samples with high analytical precision, thereby demonstrating its immense utility for biomedical diagnostics. M. Breitwieser, M. Klingele, B. Britton, S. Holdcroft, R. Zengerle, S. ThieleImproved Pt-utilization efficiency of low Pt-loading PEM fuel cell electrodes using direct membrane deposition 2015 Electrochem Commun , volume : 60, pages : 168 - 171» show abstract « hide abstract Abstract Direct membrane deposition was used to produce record platinum catalyst utilization efficiency polymer electrolyte membrane fuel cells. The novel membrane fabrication technique was applied to gas diffusion electrodes with low Pt-loadings of 0.102 and 0.029 mg/cm2. Under oxygen atmosphere and 300 kPaabs total pressure, 88 kW/gPt cathodic catalyst utilization efficiency with a symmetrical Pt-loading of 0.029 mg/cm2 on the anode and cathode side was achieved. This is 2.3 times higher than the Pt-utilization efficiency of a reference fuel cell prepared using a commercial Nafion N-211 membrane and identical catalyst layers, emphasizing that the improvement is purely attributable to the novel membrane fabrication technique. This value represents the highest Pt-utilization efficiency reported in literature. The results strongly motivate the application of employing direct membrane deposition techniques to prepare low resistance polymer electrolyte thin films in order to compensate for kinetic losses introduced when using low catalyst loadings. D. Czurratis, Y. Beyl, A. Grimm, T. Brettschneider, S. Zinober, F. Lärmer, R. ZengerleLiquids on-chip: direct storage and release employing micro-perforated vapor barrier films 2015 Lab Chip , volume : 15, pages : 2887 - 2895» show abstract « hide abstract Abstract Liquids on-chip describes a reagent storage concept for disposable pressure driven Lab-on-Chip (LoC) devices, which enables liquid storage in reservoirs without additional packaging. On-chip storage of liquids can be considered as one of the major challenges for the commercial break through of polymer-based LoC devices. Especially the ability for long-term storage and reagent release on demand are the most important aspects for a fully developed technology. On-chip storage not only replaces manual pipetting, it creates numerous advantages: fully automated processing, ease of use, reduction of contamination and transportation risks. Previous concepts for on-chip storage are based on liquid packaging solutions (e.g. stick packs, blisters, glass ampoules), which implicate manufacturing complexity and additional pick and place processes. That is why we prefer on-chip storage of liquids directly in reservoirs. The liquids are collected in reservoirs, which are made of high barrier polymers or coated by selected barrier layers. Therefore, commonly used polymers for LoC applications as cyclic olefin polymer (COP) and polycarbonate (PC) were investigated in the context of novel polymer composites. To ensure long-term stability the reservoirs are sealed with a commercially available barrier film by hot embossing. The barrier film is structured by pulsed laser ablation, which installs rated break points without affecting the barrier properties. A flexible membrane is actuated through pneumatic pressure for reagent release on demand. The membrane deflection breaks the barrier film and leads to efficient cleaning of the reservoirs in order to provide the liquids for further processing. G.Czilwik, S.K.Vashist, V.Klein, G.Roth, A.Buderer, F. von Stetten, R. Zengerle, D.MarkMagnetic chemiluminescent immunoassay for human C-reactive protein on the centrifugal microfluidics platform 2015 Rsc Adv , volume : 5, pages : 61906 - 61912» show abstract « hide abstract Abstract Human C-reactive protein (CRP) has been reported as an inflammatory biomarker with the highest reference for use in clinical practice. However, the existing analytical techniques are lacking automation and simplicity, as desired for a prospective immunoassay format for point-of-care (PoC) analysis. We have developed an automated magnetic chemiluminescent immunoassay (MCIA) on a mobile analyser for rapid PoC determination of CRP. The MCIA is fully automated after the initial loading of sample and immunoreagents at the inlet ports. The automated protocol involves the transportation of magnetic capture microparticles between adjacent reaction compartments using a set of stationary magnets, a microfluidic polymer disposable and a specific centrifugal protocol. The developed MCIA has a sample-to-answer time of 25 min and hands-on time of approximately 5 min. It detects the entire pathophysiological range of CRP, as desired for clinically-relevant high sensitivity CRP immunoassay format, i.e. 3–81 ng mL−1 in diluted human serum with a limit of detection (LOD) and limit of quantification (LOQ) of 1.5 ng mL−1 and 1.8 ng mL−1, respectively. F. Schwemmer, S. Zehnle, D. Mark, F. von Stetten, R. Zengerle, N. PaustMicrofluidic timer for timed valving and pumping in
centrifugal microfluidics 2015 Lab Chip , volume : 15, pages : 1545 - 1553» show abstract « hide abstract Abstract Accurate timing of microfluidic operations is essential for the automation of complex laboratory
workflows, in particular for the supply of sample and reagents. Here we present a new unit operation
for timed valving and pumping in centrifugal microfluidics. It is based on temporary storage of
pneumatic energy and time delayed sudden release of said energy. The timer is loaded at a relatively
higher spinning frequency. The countdown is started by reducing to a relatively lower release
frequency, at which the timer releases after a pre-defined delay time. We demonstrate timing for
1.) the sequential release of 4 liquids at times of 2.7 s ± 0.2 s, 14.0 s ± 0.5 s, 43.4 s ± 1.0 s and
133.8 s ± 2.3 s, 2.) timed valving of typical assay reagents (contact angles 36° - 78°, viscosities
0.9 mPa s - 5.6 mPa s) and 3.) “on demand” valving of liquids from 4 inlet chambers in any user defined
sequence controlled by the spinning protocol. The microfluidic timer is compatible to all wetting
properties and viscosities of common assay reagents and does neither require assistive equipment, nor
coatings. It can be monolithically integrated into a microfluidic test carrier and is compatible to
scalable fabrication technologies such as thermoforming or injection molding. G. Czilwik, I. Schwarz, M. Keller, S. Wadle, S. Zehnle, F. von Stetten, D. Mark, R. Zengerle, N. PaustMicrofluidic vapor-diffusion barrier for pressure reduction in fully closed PCR modules 2015 Lab Chip , volume : 15, pages : 1084 - 1091» show abstract « hide abstract Abstract Microfluidic systems for polymerase chain reaction (PCR) should be fully closed to avoid vapor loss and to exclude the risk of contaminating the test environment. In closed systems however, the high temperatures of up to 95°C associated with PCR cause high overpressures up to 100 kPa, dominated by the increase of vapor partial pressure upon evaporation. Such high overpressures pose challenges to the mechanical stability of microfluidic chips as well as to the liquid handling in integrated sample-to-answer systems. In this work, we drastically reduce the pressure increase in fully closed PCR systems by integrating a microchannel that serves as a vapor-diffusion barrier (VDB), separating the liquid-filled PCR chamber from an auxiliary air chamber. In such configurations, propagation of vapor from the PCR chamber into the auxiliary air chamber and as a consequence the increase of pressure is limited by the slow diffusion process of vapor through the VDB. At temperature increase from 23°C to 95°C, we demonstrate the reduction of overpressure from more than 80 kPa without the VDB to only 35 kPa with the VDB. We further demonstrate proper function of VDB and its easy integration with downstream processes for PCR based nucleic acid amplification within centrifugal microfluidics. Without integration of the VDB, malfunction due to pressure-induced delamination of the microfluidic chip occurred. G. Czilwik, D. Baumann, D. Mark, R. Zengerle, F. von StettenMikrofluidische Automatisierung in der Molekulardiagnostik 2015 BIOspektrum , volume : 21, pages : 622 - 624» show abstract « hide abstract Abstract Easy-to-use point-of-care (POC) tests provide rapid diagnostic results
near the patient, enabling fast decision-making in patient management.
However, the implementation of automated molecular diagnostic POC
tests still faces technical challenges. We demonstrate a highly sensitive
POC platform for automated molecular diagnostics of neonatal sepsis
that uses a mobile analyzer and unit-use test carriers. S. Vierrath, L. Zielke, R. Moroni, A. Mondon, D. R. Wheeler, R. Zengerle, S. ThieleMorphology of nanoporous carbon-binder domains in Li-ion batteries—A FIB-SEM study 2015 Electrochem Commun , volume : 60, pages : 176 - 179» show abstract « hide abstract Abstract FIB-SEM tomography is used to reconstruct the carbon-binder domain (CBD) of a LiCoO2 battery cathode (3.9 × 5 × 2.3 μm3) with contrast enhancement by ZnO infiltration via atomic layer deposition. We calculate the porosity inside the CBD (57.6%), the cluster-size distribution with a peak at 54 nm, and the pore-size distribution with a peak at 64 nm. The tortuosities of the pore space (1.6–2.0) and the CBD (2.3–3.5) show a mild anisotropy, which is attributed to the fabrication process. A comparison to a modeled homogenous CBD reveals that clustering in the CBD decreases its electronic conductivity while increasing the ionic diffusivity. To account for the higher calculated diffusivity compared to experimental values from literature, a simple binder swelling model is implemented, suggesting a swelling of 75 vol%. The prevention of both clustering and swelling could increase the volume available for active material and therefore the energy density. S. Zehnle, F. Schwemmer, R. Bergmann, F. von Stetten, R. Zengerle, N. PaustPneumatic siphon valving and switching in centrifugal
microfluidics controlled by rotational frequency or rotational
acceleration 2015 Microfluid Nanofluid , volume : 19, pages : 1259 - 1269» show abstract « hide abstract Abstract Air-pressure-mediated, pneumatic siphon
valves employ temporary storage and subsequent release
of pneumatic energy, exclusively controlled by rotation
of the disk. Implementation is easy, and robust valves can
be integrated in a monolithic way at minimum additional
costs. However, so far, pneumatic siphon valving requires
deceleration from high to low rotational frequencies. Valve
opening is performed always when the rotation of the disk
drops below a critical rotational frequency. To overcome
this limitation, we introduce new concepts for pneumatic
siphon valving which enable operation of the disk at any
rotational frequency without unwanted bursts of the siphon
valves. Thus, the design space for pneumatic siphon valves
in centrifugal microfluidics is significantly extended.
Three types of pneumatic siphon valves are presented with
release control at (1) rotational frequencies between 25
and 48 Hz, (2) positive rotational accelerations between
1 and 22 Hz s−1, and (3) negative rotational accelerations
between 5 and 20 Hz s−1. Finally, we combine two valve
types to realize robust switching into two fluidic paths with flow rate ratios of 94/6 and 0/100. C. Köhler, L. Bleck, M. Frei, R. Zengerle, S. KerzenmacherPoisoning of Highly Porous Platinum Electrodes by Amino Acids and Tissue Fluid Constituents 2015 ChemElectroChem , volume : 2, pages : 1785 - 1793» show abstract « hide abstract Abstract The first comprehensive study of the poisoning behavior of physiological amino acids and important tissue fluid constituents on porous platinum electrodes was performed. On the basis of chronoamperometry under physiological conditions, the results are highly relevant for the development of enzyme-free implantable glucose fuel cells and possibly also glucose sensors. The strongest poisoning was exhibited by positively charged alkaline amino acids and by some of the neutral amino acids, as well as by uric acid and creatinine. In contrast to previous work, sulfur-containing amino acids showed no poisoning effect. This was explained by the use of highly porous platinum electrodes in the current study and experimental methods that were more relevant for practical applications. Furthermore, comprehensive analysis regarding the degree of recovery in the absence of poisoning species and the extent of electrode regeneration by cyclic voltammetry was performed for each of the amino acids and physiological substances. M. Klingele, R. Zengerle, S. ThieleQuantification of artifacts in scanning electron microscopy tomography: Improving the reliability of calculated transport parameters in energy applications such as fuel cell and battery electrodes 2015 J Power Sources , volume : 275, pages : 852 - 859» show abstract « hide abstract Abstract Focused ion beam and scanning electron microscopy tomography (FIB-SEMt) is commonly used to extract reactant transport relevant parameters from nano-porous materials in energy applications, such as fuel cells or batteries. Here we present an approach to virtually model the errors in FIB-SEMt which are caused by the FIB cutting distance. The errors are evaluated in terms of connectivity, solid volume fraction (SVF), conductivity, diffusivity, as well as mean grain and pore sizes. For state-of-the-art FIB-SEMt experiments, where a hydrogen fuel cell catalyst layer with 60 nm mean grain size and 40% SVF is sectioned with a cutting distance of 15 nm, the error in our simulation ranges up to 51% (conductivity), whereas other parameters remain largely unaffected (Laplace diffusivity, 4%). We further present a method, employing virtual coarsening and back interpolation, to reduce FIB cutting distance errors in all investigated parameters. Both error evaluation and correction are applicable to sphere based porous materials with relevance for the energy conversion and storage sector such as polymer electrolyte membrane fuel cell catalyst layer (PEMFC CL), battery carbon binder domain (CBD) or supercapacitor electrodes. G. Czilwik, T. Messinger, O. Strohmeier, S. Wadle, F. von Stetten, N. Paust, G. Roth, R. Zengerle, P. Saarinen, J. Niittymäki, K. McAllister, O. Sheils, J. O'Leary, D. MarkRapid and fully automated bacterial pathogen detection on a centrifugal-microfluidic LabDisk using highly sensitive nested PCR with integrated sample preparation 2015 Lab Chip , volume : 15, pages : 3749 - 3759» show abstract « hide abstract Abstract Diagnosis of infectious diseases suffers from long turnaround times for gold standard culture-based identification of bacterial pathogens, therefore impeding timely specific antimicrobial treatment based on laboratory evidence. Rapid molecular diagnostics-based technologies enable detection of microorganisms within hours however cumbersome workflows and complex equipment still prevent their widespread use in the routine clinical microbiology setting. We developed a centrifugal-microfluidic “LabDisk” system for rapid and highly-sensitive pathogen detection on a point-of-care analyser. The unit-use LabDisk with pre-stored reagents features fully automated and integrated DNA extraction, consensus multiplex PCR pre-amplification and geometrically-multiplexed species-specific real-time PCR. Processing merely requires loading of the sample and DNA extraction reagents with minimal hands-on time of approximately 5 min. We demonstrate detection of as few as 3 colony-forming-units (cfu) of Staphylococcus warneri, 200 cfu of Streptococcus agalactiae, 5 cfu of Escherichia coli and 2 cfu of Haemophilus influenzae in a 200 μL serum sample. The turnaround time of the complete analysis from “sample-to-result” was 3 h and 45 min. The LabDisk consequently provides an easy-to-use molecular diagnostic platform for rapid and highly-sensitive detection of bacterial pathogens without requiring major hands-on time and complex laboratory instrumentation. F. Stumpf, J. Schoendube, A. Gross, C. Rath, S. Niekrawietz, P. Koltay, G. RothSingle-cell PCR of genomic DNA enabled by automated single-cell printing for cell isolation 2015 Biosens Bioelectron , volume : 69, pages : 301 - 306» show abstract « hide abstract Abstract Single-cell analysis has developed into a key topic in cell biology with future applications in personalized medicine, tumor identification as well as tumor discovery (Editorial, 2013). Here we employ inkjet-like printing to isolate individual living single human B cells (Raji cellline) and load them directly into standard PCR tubes. Single cells are optically detected in the nozzle of the microfluidic piezoelectric dispenser chip to ensure printing of droplets with single cells only. The printing process has been characterized by using microbeads (10 µm diameter) resulting in a single bead delivery in 27 ou tof 28 cases and relative positional precision of ± 350 µm at a printing distance of 6 mm between nozzle and tube lid. Process-integrated optical imaging enabled to identify the printing failure as void droplet and to exclude it from downstream processing. PCR of truly single-cell DNA was performed without pre-amplification directly from single Raji cells with 33% success rate (N=197) and Cq values of 36.3 ± 2.5. Additionally single cell whole genome amplification (WGA) was employed to pre-amplify the single-cell DNA by a factor of >1000. This facilitated subsequent PCR for the same gene yielding a success rate of 64% (N=33) which will allow more sophisticated downstream analysis like sequencing, electrophoresis or multiplexing. J. Schoendube, D. Wright, R. Zengerle, P. KoltaySingle-cell printing based on impedance detection 2015 Biomicrofluidics , volume : 9, page : 014117» show abstract « hide abstract Abstract Label-free isolation of single cells is essential for the growing field of single-cell
analysis. Here, we present a device which prints single living cells encapsulated in
free-flying picoliter droplets. It combines inkjet printing and impedance flow
cytometry. Droplet volume can be controlled in the range of 500 pl–800 pl by piezo
actuator displacement. Two sets of parallel facing electrodes in a 50 µm x 55 µm
channel are applied to measure the presence and velocity of a single cell in
real-time. Polystyrene beads with <5% variation in diameter generated signal
variations of 12%–17% coefficients of variation. Single bead efficiency (i.e.,
printing events with single beads vs. total number of printing events) was 73%611%
at a throughput of approximately 9 events/min. Viability of printed HeLa cells and
human primary fibroblasts was demonstrated by culturing cells for at least eight days. C. E. Blanchet, A. Spilotros, F. Schwemmer, M. A. Graewert, A. Kikhney, C. M. Jeffries, D. Franke, D. Mark, R. Zengerle, F. Cipriani, S. Fiedler, M. Roessle, D. I. SvergunaVersatile sample environments and automation for
biological solution X-ray scattering experiments at
the P12 beamline (PETRA III, DESY) 2015 J Appl Crystallogr , volume : 48, pages : 431 - 443» show abstract « hide abstract Abstract A high-brilliance synchrotron P12 beamline of the EMBL located at the
PETRA III storage ring (DESY, Hamburg) is dedicated to biological smallangle
X-ray scattering (SAXS) and has been designed and optimized for
scattering experiments on macromolecular solutions. Scatterless slits reduce the
parasitic scattering, a custom-designed miniature active beamstop ensures
accurate data normalization and the photon-counting PILATUS 2M detector
enables the background-free detection of weak scattering signals. The high flux
and small beam size allow for rapid experiments with exposure time down to 30–
50 ms covering the resolution range from about 300 to 0.5 nm. P12 possesses a
versatile and flexible sample environment system that caters for the diverse
experimental needs required to study macromolecular solutions. These include
an in-vacuum capillary mode for standard batch sample analyses with robotic
sample delivery and for continuous-flow in-line sample purification and
characterization, as well as an in-air capillary time-resolved stopped-flow setup.
A novel microfluidic centrifugal mixing device (SAXS disc) is developed for a
high-throughput screening mode using sub-microlitre sample volumes. Automation
is a key feature of P12; it is controlled by a beamline meta server, which
coordinates and schedules experiments from either standard or nonstandard
operational setups. The integrated SASFLOWpipeline automatically checks for
consistency, and processes and analyses the data, providing near real-time
assessments of overall parameters and the generation of low-resolution models
within minutes of data collection. These advances, combined with a remote
access option, allow for rapid high-throughput analysis, as well as time-resolved
and screening experiments for novice and expert biological SAXS users. J. Schoendube, A. Yusof, K. Kalkandjiev, R. Zengerle, P. KoltayWafer level fabrication of single cell dispenser chips with integrated electrodes for particle detection
2015 J Micromech Microeng , volume : 25, page : 025008» show abstract « hide abstract Abstract This work presents the microfabrication and experimental evaluation of a dispenser chip,
designed for isolation and printing of single cells by combining impedance sensing and
drop-on-demand dispensing. The dispenser chip features 50 × 55 μm (width × height)
microchannels, a droplet generator and microelectrodes for impedance measurements. The
chip is fabricated by sandwiching a dry film photopolymer (TMMF) between a silicon
and a Pyrex wafer. TMMF has been used to define microfluidic channels, to serve as low
temperature (75 °C) bonding adhesive and as etch mask during 300 μm deep HF etching of the
Pyrex wafer. Due to the novel fabrication technology involving the dry film resist, it became
possible to fabricate facing electrodes at the top and bottom of the channel and to apply
electrical impedance sensing for particle detection with improved performance. The presented
microchip is capable of dispensing liquid and detecting microparticles via impedance
measurement. Single polystyrene particles of 10 μm size could be detected with a mean signal
amplitude of 0.39 ± 0.13 V (n = 439) at particle velocities of up to 9.6 mm s−1 inside the chip. back to the year overview L. Zielke, T. Hutzenlaub, D. R. Wheeler, I. Manke, T. Arlt, N. Paust, R. Zengerle, S. ThieleA Combination of X-Ray Tomography and Carbon Binder Modeling: Reconstructing the Three Phases of LiCoO2 Li-Ion Battery Cathodes 2014 Adv Energy Mater , volume : 4, page : 1301617» show abstract « hide abstract Abstract X-ray tomography allows the active-material domain (LiCoO2) of Li-ion battery cathodes to be imaged, but it is unable to resolve the carbon-binder domain (CBD). Here, a new method for creating a complete 3D representation (virtual design) of all three phases of a cathode is provided; this includes the active-material domain, the CBD, and the electrolyte-filled pore space. It combines X-ray tomographic data of active material with a statistically modeled CBD. Two different statistical CBD morphology models are compared as examples: i) a random cluster model representing a standard mixture of carbon black and polyvenylidene fluoride (PVDF) and ii) a fiber model. The transport parameters are compared in a charged and a discharged cathode. The results demonstrate that the CBD content and morphology changes the ionic and electronic transport parameters dramatically and thus cannot be neglected. Calculations yield that the fiber model shows up to three times higher electrical conductivity at the same CBD content (discharged case) and better ionic diffusion conditions for all CBD contents. In the charged case, the morphology impact on electrical conduction is small. This effective method to generate transport parameters for different CBDs can be transferred to other CBD morphologies and electrodes. S.K. Vashist, G. Czilwik, T. van Oordt, F. von Stetten, R. Zengerle,, E.M. Schneider, J.H.T. LuongA rapid one-step kinetics-based immunoassay procedure for the highly-sensitive detection of C-reactive protein 2014 Protocol Exchange M. Hoehl, E. Schulte Bocholt, A. Kloke, N. Paust, F. von Stetten, R. Zengerle, J. Steigert, A. SlocumA versatile-deployable bacterial detection system for food and environmental safety based on LabTube-automated DNA purification, LabReader-integrated amplification, readout and analysis 2014 Analyst , volume : 139, pages : 2788 - 2798» show abstract « hide abstract Abstract Contamination of foods is a public health hazard that episodically causes thousands of deaths and sickens
millions worldwide. To ensure food safety and quality, rapid, low-cost and easy-to-use detection methods
10 are desirable. Here, the LabSystem is introduced for integrated, automated DNA purification,
amplification and detection. It consists of a disposable, centrifugally-driven DNA purification platform
(LabTube) and the subsequent amplification and detection in a low-cost UV/vis-reader (LabReader). For
demonstration of the LabSystem in the context of food safety, purification of Escherichia coli (nonpathogenic
E. coli and pathogenic verotoxin-producing E. coli (VTEC)) in water and milk, and the
15 product-spoiler Alicyclobacillus acidoterrestris (A. acidoterrestris) in apple juice was integrated and
optimized in the LabTube. Inside the LabReader, the purified DNA was amplified, readout and analyzed
using both qualitative isothermal loop-mediated DNA amplification (LAMP) and quantitative real-time
PCR. For the LAMP-LabSystem, the combined detection limits for purification and amplification of
externally lysed VTEC and A. acidoterrestris is 102-103 cell-equivalents. In the PCR-LabSystem for
E. coli cells, the quantification limit is 102 20 cell-equivalents including LabTube-integrated lysis. The
demonstrated LabSystem only requires a laboratory centrifuge (to operate the disposable, fully closed
LabTube) and the low-cost LabReader for DNA amplification, readout and analysis. Compared with
commercial DNA amplification devices, the LabReader improves sensitivity and specificity by the
simultaneous readout of four wavelengths and the continuous readout during temperature cycling. The
25 use of a detachable eluate tube as an interface affords semi-automation of the LabSystem, which does not
require specialized training. It reduces hands-on time from about 50 to 3 min with only two handling
steps: sample input and transfer of the detachable detection tube. S. K. Vashist, O. Mudanyali, E. M. Schneider, R. Zengerle, A. OzcanCellphone-based devices for bioanalytical sciences 2014 Anal Bioanal Chem , volume : 406, issue : 14, pages : 3263 - 3277» show abstract « hide abstract Abstract During the last decade, there has been a rapidly
growing trend toward the use of cellphone-based devices
(CBDs) in bioanalytical sciences. For example, they have
been used for digital microscopy, cytometry, read-out of immunoassays and lateral flow tests, electrochemical and surface
plasmon resonance based bio-sensing, colorimetric detection
and healthcare monitoring, among others. Cellphone can be
considered as one of the most prospective devices for the
development of next-generation point-of-care (POC)
diagnostics platforms, enabling mobile healthcare delivery
and personalized medicine. With more than 6.5 billion
cellphone subscribers worldwide and approximately 1.6 billion
new devices being sold each year, cellphone technology is also
creating new business and research opportunities. Many
cellphone-based devices, such as those targeted for diabetic
management, weight management, monitoring of blood
pressure and pulse rate, have already become commerciallyavailable
in recent years. In addition to such monitoring
platforms, several other CBDs are also being introduced,
targeting e.g., microscopic imaging and sensing applications
for medical diagnostics using novel computational algorithms
and components already embedded on cellphones. This report
aims to review these recent developments in CBDs for
bioanalytical sciences along with some of the challenges
involved and the future opportunities. M. Hoehl, M. Weissert, A. Dannenberg, T. Nesch, N. Paust, F. von Stetten, R. Zengerle, A. Slocum, J. SteigertCentrifugal LabTube platform for fully automated DNA purification and LAMP amplification based on an integrated, low-cost heating-system 2014 Biomed Microdevices , volume : 16, issue : 3, pages : 375 - 385» show abstract « hide abstract Abstract This paper introduces a disposable battery-driven heating system for loop-mediated isothermal DNA amplification (LAMP) inside a centrifugally-driven DNA purification platform (LabTube). We demonstrate LabTube-based fully automated DNA purification of as low as 100 cell-equivalents of verotoxin-producing Escherichia coli (VTEC) in water, milk and apple juice in a laboratory centrifuge, followed by integrated and automated LAMP amplification with a reduction of hands-on time from 45 to 1 min. The heating system consists of two parallel SMD thick film resistors and a NTC as heating and temperature sensing elements. They are driven by a 3 V battery and controlled by a microcontroller. The LAMP reagents are stored in the elution chamber and the amplification starts immediately after the eluate is purged into the chamber. The LabTube, including a microcontroller-based heating system, demonstrates contamination-free and automated sample-to-answer nucleic acid testing within a laboratory centrifuge. The heating system can be easily parallelized within one LabTube and it is deployable for a variety of heating and electrical applications. K. Dolch, J. Danzer, T. Kabbeck, B. Bierer, J. Erben, A. H. Förster, J. Maisch, P. Nick, S. Kerzenmacher, J. GescherCharacterization of microbial current production as a function of microbe-electrode-interaction 2014 Bioresource Technol , volume : 157, pages : 284 - 292» show abstract « hide abstract Abstract Microbe–electrode-interactions are keys for microbial fuel cell technology. Nevertheless, standard measurement routines to analyze the interplay of microbial physiology and material characteristics have not been introduced yet. In this study, graphite anodes with varying surface properties were evaluated using pure cultures of Shewanella oneidensis and Geobacter sulfurreducens, as well as defined and undefined mixed cultures. The evaluation routine consisted of a galvanostatic period, a current sweep and an evaluation of population density. The results show that surface area correlates only to a certain extent with population density and anode performance. Furthermore, the study highlights a strain-specific microbe–electrode-interaction, which is affected by the introduction of another microorganism. Moreover, evidence is provided for the possibility of translating results from pure culture to undefined mixed species experiments. This is the first study on microbe–electrode-interaction that systematically integrates and compares electrochemical and biological data. S. Sané, C. Heilemann, P. Salvei, S. Rubenwolf, C. Jolivalt, C. Madzak, R. Zengerle, P. J. Nielsen, S. KerzenmacherEnzymatic fuel cells solely supplied with unpurified cellobiose dehydrogenaseand laccase in microorganism´s culture supernatans 2014 ChemElectroChem , volume : 1, pages : 1886 - 1894» show abstract « hide abstract Abstract Enzymatic electrodes have great potential for catalysing the direct conversion of chemical compounds into electricity with the use of redox enzymes. However, expensive and time-consuming enzyme purification and the frequent need to add mediators are considered as drawbacks of enzymatic electrodes. We report a biofuel cell at pH 5, supplied with the unpurified enzymes laccase and cellobiose dehydrogenase (CDH) in crude culture supernatant, without the further addition of mediators. A maximum power output of 6.2±1.2 μW cm−2 was achieved by using supernatants containing laccase from Trametes versicolor (2.84 UmL−1) and CDH (0.90 UmL−1) from a recombinant yeast Yarrowia lipolytica YPC4. In comparison, the supply of purified enzymes (laccase: 2.40 UmL−1, CDH: 0.15 UmL−1) in a buffer solution yielded only about a twofold higher power density. Our results demonstrate the feasibility of using unpurified laccase and CDH in an enzymatic biofuel cell, which can simplify its construction and operation. S. K. Vashist, E.M. Schneider, R. Zengerle, F. von Stetten, J.H.T. LuongGraphene-based rapid and highly-sensitive immunoassay for C-re
active protein using a smartphone-based colorimetric reader 2014 Biosens Bioelectron , volume : 66, pages : 169 - 176» show abstract « hide abstract Abstract A novel immunoassay (IA) has been developed for human C-reactive protein (CRP), an important biomarker and tissue preserving factor for infection and inflammation. Graphene nanoplatelets (GNP) and 3-aminopropyltriethoxysilane (APTES) were admixed and covalently attached to a polystyrene based-microtiter plate (MTP), pretreated with KOH. The resulting surface served as a stable layer for the covalent attachment of the anti-human CRP antibody. The IA procedure was based on the one-step kinetics-based sandwich IA employing a minimum number of process steps, whereas the enzymatic reaction solution was monitored by a smartphone-based colorimetric reader. With a limit of detection and a limit of quantification of 0.07 ng mL−1 and 0.9 ng mL−1, it precisely detected CRP spiked in diluted human whole blood and plasma as well as the CRP levels in clinical plasma samples. The results obtained for “real-world” patient samples agreed well with those of the conventional immunosorbent assay and the clinically-accredited analyzer-based IA. The antibody-bound GNP-functionalized MTPs retained its original activity after 6 weeks of storage in 0.1 M PBS, pH 7.4 at 4 °C. K.G. Kraiczek, R. Bonjour, Y. Salvadé, R. ZengerleHighly Flexible UV-Vis Radiation Sources and Novel Detection Schemes for Spectrophotometric HPLC Detection 2014 Anal Chem , volume : 86, issue : 2, pages : 1146 - 1152» show abstract « hide abstract Abstract The concept and performance of the first multiwavelength deep UV
light-emitting-diode-based high-performance liquid chromatography (HPLC)
absorbance detector are presented. In single-wavelength mode and with optical
reference, the limit of detection (LOD) is comparable to conventional state-of-theart
HPLC absorbance detectors. In multiwavelength modeat present up to eight
wavelengths without optical referencethe LOD is about 10 times higher than in
single-wavelength mode. Multiplexing and demultiplexing methods are used to
separate chromatographic signals in multiwavelength mode and keeps the detector
configuration simple and yet flexible. Depending on the operation mode, stray
light is either totally negligible or controlled electronically and digitally. E. Kipf, R. Zengerle, J. Gescher, S. KerzenmacherHow Does the Choice of Anode Material Influence
Electrical Performance? A Comparison of Two Microbial
Fuel Cell Model Organisms
2014 ChemElectroChem , volume : 1, pages : 1849 - 1853» show abstract « hide abstract Abstract The influence of the anode material on the electrical performance
of the two microbial fuel cell model organisms Geobacter
sulfurreducens and Shewanella oneidensis is investigated.
High-surface-area activated carbon and low-surface-area
graphite felt are compared in terms of polarization curves
under quasi-steady-state conditions. Unexpectedly, G. sulfurreducens
exhibits similar current densities up to 700 mAcm_2 independent
of the anode material. This is ~50% higher than
steady-state values reported previously. The negligible influence
of electrode material on the electrical performance of
G. sulfurreducens is attributed to the fact that it performs only
direct electron transfer, but forms thick biofilms. In contrast,
S. oneidensis, relying mainly on mediated electron transfer, apparently
makes better use of high-surface-area activated
carbon and achieves higher current densities compared to
graphite felt. This underlines the importance of tailoring anode
materials according to the used organisms. O. Fokina, J. Eipper, L. Winandy, S. Kerzenmacher, R. FischerImproving the performance of a biofuel cell cathode with laccase from Pycnoporus sanguineus 2014 Bioresource Technol , volume : 175C, pages : 445 - 453 T. van Oordt, Y. Barb, R. Zengerle, F. von StettenLamination of Polyethylene Composite Films by Ultrasonic Welding: Investigation of Peel Behavior and Identification of Optimum Welding Parameters 2014 J Appl Polym Sci , volume : 131, pages : 40291 - 40298» show abstract « hide abstract Abstract The lamination of different polyethylene (PE) composite films by ultrasonic welding to fabricate peelable seals that open
at defined burst pressures is investigated. The sealing time, pressure, and amplitude were varied within the range of 100–400 ms, 50–
250 kPa, and 12–24 mm, respectively. T-peel tests and electron micrographs revealed four different peel regimes, depending on the
parameter combination: (I) Interlaminar peeling at low-peel strength with uniform peeling along a weakly bonded PE lamination
layer; (II) transition tearing at intermediate peel strength showing areas of interlaminar peeling and translaminar tearing; (III) translaminar
tearing at high-peel strength showing tears through the entire film; and, (IV) undefined tearing at varying tear strength occurring
when vibration effects during welding lead to insufficient contact of the films or high pressures lead to a displacement of PE.
This study will allow the systematic adjustment of ultrasonic welding parameters for PE films. D. Liang, J. Zhang, M.T. Govindaiah, L. Tanguy, A. Ernst, R. Zengerle, P. KoltayLiquid volume measurement method for the picoliter to nanoliter volume range based on quartz crystal microbalance technology 2014 Meas Sci Technol , volume : 25, page : 095302» show abstract « hide abstract Abstract In this article, a quantitative liquid volume measurement method for the sub-nanoliter range using a quartz crystal microbalance (QCM) is described and experimentally analyzed. The primary measurement device to determine the volume of small liquid droplets is a QCM sensor coated with a surface-attached hydrogel to improve the mechanical coupling of the liquid to the sensor surface. An experimental evaluation of measured volumes in the range of 3 nl to 15 nl in normal room conditions has been performed with three identical sensors prepared with a PDMAA-1%MaBP hydrogel coating with a thickness of 1.5 µm ± 0.12 µm. A linearity of R2 more than 0.87, an average coefficient of variation (CV) within one experimental run of 5.7%, a mean absolute relative bias of 5.5%, and a sensor-to-sensor variation of 6.3% have been experimentally determined. The feasibility of this method has also been experimentally proven for the picoliter volume range down to 200 pl, with an average CV of 5.3% and a mean absolute relative bias of 6.5%. Furthermore, a stability evaluation consisting of 10 experimental series with approximately 150 measurements over the course of one week has been performed. This evaluation showed that the experimental setup, although exhibiting highly consistent performance within one measurement run, is not yet reproducible enough for long-term and repeated use because of undefined swelling and crack formation in the hydrogel layer. The low reproducibility implies a relatively high expanded uncertainty, with k = 2 according to the JCGM 'Evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement' (GUM) for the total measurement method of approximately 3.82 nl when measuring a 10 nl liquid droplet. Nevertheless, the QCM method as described here contributes to significant progress beyond the state-of-the-art that might allow new opportunities for precise measurement of sub-nanoliter liquid volumes. K. Mutschler, S. Dwivedi, S. Kartmann, S. Bammesberger, P. Koltay, R. Zengerle, L. TanguyMulti physics network simulation of a solenoid dispensing valve 2014 Mechatronics , volume : 24, pages : 209 - 221» show abstract « hide abstract Abstract significant
effects in a complete technical system. In a solenoid dispensing valve the involved physical effects
are electro-magnetic (coil and magnet interaction), fluid flow and fluid structure interaction. It is challenging
and time consuming to establish a full model description of these different effects even by using
the most up-to-date Computational Fluid Dynamics (CFDs) software tools. This article therefore presents
an alternative approach using network simulation methods for modelling of a dispensing valve using the
simulation software SABER (Synopsys). To create the model, the different parts of the valve and the relevant
physical effects occurring therein are described by partial differential equations and implemented
as lumped elements. The lumped elements are then linked together to form a complete model of the dispensing
valve including electrical, mechanical and fluid dynamic properties. A comparison with experimental
data obtained from a real valve is presented at the end of the paper to discuss and validate the
model. In particular the correct prediction of the dispensed liquid volume in dependence of the main
parameters like pressure and opening time are considered. Using ab initio simulation deviations of the
predicted dispensed liquid volume from the experimental results in the range 0.65–7.4% was found for
different actuating pressures at valve opening times larger than 20 ms. M. Salzer, S. Thiele, R. Zengerle, V. SchmidtOn the importance of FIB-SEM specific segmentation algorithms for porous media 2014 Mater Charact , volume : 95, pages : 36 - 43» show abstract « hide abstract Abstract A new algorithmic approach to segmentation of highly porous three dimensional image data gained by focused ion beam tomography is described which extends the key-principle of local threshold backpropagation described in [1]. The technique of focused ion beam tomography has shown to be capable of imaging the microstructure of functional materials. In order to perform a quantitative analysis on the corresponding microstructure a segmentation task needs to be performed. However, algorithmic segmentation of images obtained with focused ion beam tomography is a challenging problem for highly porous materials if filling the pore phase, e.g. with epoxy resin, is difficult. The grey intensities of individual voxels are not sufficient to determine the phase represented by them and usual thresholding methods are not applicable. We thus propose a new approach to segmentation, that pays respect to the specifics of the imaging process of focused ion beam tomography. As an application of our approach, the segmentation of three dimensional images for a cathode material used in polymer electrolyte membrane fuel cells is discussed. We show that our approach preserves significantly more of the original nanostructure than an thresholding approach. S.K. Vashist, G. Czilwik, T. van Oordt, F. von Stetten, R. Zengerle, E.M. Schneider, J.H.T. LuongOne-step kinetics-based immunoassay for the highly-sensitive detection of C-reactive protein in less than 30 minutes 2014 Anal Biochem , volume : 456, pages : 32 - 37» show abstract « hide abstract Abstract The article reveals a rapid sandwich enzyme-linked immunosorbent assay (ELISA) for the
highly-sensitive detection of human C-reactive protein (CRP) in less than 30 min. It employs
a one-step kinetics-based highly simplified and cost-effective sandwich ELISA procedure
with minimum process steps. The procedure involves the formation of a sandwich immune
complex on capture anti-human CRP antibody-bound Dynabeads® in 15 min followed by two
magnet-assisted washings and one enzymatic reaction. The developed sandwich ELISA
detects CRP in the dynamic range of 0.3-81 ng mL-1 with a limit of detection and analytical
sensitivity of 0.4 ng mL-1 and 0.7 ng mL-1, respectively. It detects CRP spiked in diluted
human whole blood and serum with high analytical precision as confirmed by conventional
sandwich ELISA. Moreover, the results of the developed ELISA for the determination of
CRP in the ethylenediaminetetraacetic acid (EDTA) plasma samples of patients are in good
agreement with those obtained by the conventional ELISA. The developed immunoassay has
immense potential for the development of rapid and cost-effective in vitro diagnostic kits. M. Pospischil, T. Fellmeth, A. Brand, S. Nold, M. Kuchler, M. Klawitter, H. Gentischer, M. König, M. Hörteis, L. Wende, O. Doll, R. Zengerle, F. Clement, D. BiroOptimizing fine line dispensed contact grids 2014 Energy Procedia , volume : 55, pages : 693 - 701» show abstract « hide abstract Abstract Previous studies on dispensing as an alternative front side metallization process in crystalline silicon photovoltaics demonstrated,
how an adaption of paste rheology allows for a precise adjustment of contact finger geometry in a wide range. In order to
demonstrate the benefit of this advantage, the analytical simulation tool Gridmaster was extended to observe the effect of various
geometrical parameters on solar cell results and manufacturing costs. In addition, respective geometrical parameters of thick film
printed contact fingers were determined using a special in house developed tool based on MATLAB. As a result, contact
geometries as achievable by means of ultrafine line dispensing are ideally suited for contacting silicon solar cells. Compared with
standard fine line single screen printed finger geometries, an efficiency increase of up to Δ = 0.4%abs. as well as a reduction of
manufacturing costs of 1 €ct./Wp on module level can be achieved using dispensing technology. In order to obtain suitable data,
simulation results were compared with solar cell results on industrial pre-processed Cz-Si p-type wafer material applying the
novel ten nozzle parallel fine line dispensing unit. Therefore, a new dispensing paste was developed combining optimum optical
finger aspect ratios of ARo = 0.7 with excellent contacting behavior. A successful first test of applicability already led to a
maximum cell efficiency of = 18.7%, demonstrated on an industrial emitter with a sheet resistance of around Rsh = 90Ω/sq. C. Köhler, M. Frei, R. Zengerle, S. KerzenmacherPerformance Loss of a Pt-Based Implantable Glucose Fuel Cell in Simulated Tissue and Cerebrospinal Fluids 2014 ChemElectroChem , volume : 1, pages : 1895 - 1900» show abstract « hide abstract Abstract We present an electrode-resolved analysis of the performance
of platinum-based abiotically catalyzed glucose fuel cells in realistically
simulated tissue fluid (STF) and cerebrospinal fluid
(SCF). The presence of amino acids and small organic molecules
at physiological concentration leads to a drastic breakdown
in fuel cell voltage, resulting in a maximum lifetime of
19 h in STF or 37 h in SCF. The performance loss mainly originates
from catalyst poisoning at the anode, which causes 92%
or 80% of the overall fuel cell voltage loss in STF or SCF, respectively.
The results underline the necessity to further investigate
and improve catalyst poisoning at the anode under realistic
body conditions in order to improve the lifetime of platinum-
based implantable glucose fuel cells. C. Escadafal, O. Faye, A. A. Sall, O. Faye, M. Weidmann, O. Strohmeier, F. von Stetten, J. Drexler, M. Eberhard, M. Niedrig, P. PatelRapid molecular assys for the detection of yellow fever virus in low-resource settings 2014 Plos Neglect Trop D , volume : 8, issue : 3, page : e2730» show abstract « hide abstract Abstract Despite the use of a safe and effective vaccine, yellow fever virus is still causing hundreds of thousands of infections and tens of thousands of deaths every year. The disease is widespread in South America and Africa where several outbreaks have occurred in the past years. As the disease is difficult to distinguish from other illnesses during its early stage, it is necessary to develop reliable, rapid and simple diagnostic methods to confirm YF cases to be able to respond effectively to outbreaks through vaccination and vector control. In this study, we describe the development a diagnostic method for YFV, using an isothermal technology called recombinase polymerase amplification which allows detection of the virus within 20 minutes, using a portable and easy-to-use device. The YFV RPA assay proved to be a specific and sensitive detection method during testing in the laboratory and under field conditions in Senegal. O. Strohmeier, N. Marquart, D. Mark, G. Roth, R. Zengerle, F. von StettenReal-time PCR based detection of a panel of foodborne
pathogens on a centrifugal microfluidic
“LabDisk” with on-disk quality controls and
standards for quantification 2014 Anal Methods-uk , volume : 6, pages : 2038 - 2046 M. Rombach, D. Kosse, B. Faltin, S. Wadle, G. Roth, R. Zengerle, F. von StettenReal-time stability testing of air-dried primers and
fluorogenic hydrolysis probes stabilized by trehalose
and xanthan 2014 Biotechniques , volume : 57, issue : 3, pages : 151 - 155» show abstract « hide abstract Abstract A method for conserving primers and differently labeled fluorogenic hydrolysis (i.e., TaqMan) probes at ambient
conditions is presented. Primers and hydrolysis probes with four different fluorophore-quencher combinations (6-
FAM–BHQ1, HEX–BHQ1, ROX–BHQ650, and Cy5–BHQ2) were mixed with trehalose and xanthan at final concentrations
of 56 mM and 2.78 mM, respectively. Mixtures were air-dried at 23°C for 30 min on strips composed
of cyclo olefin polymer (COP), a material widely used in the manufacturing of in vitro diagnostic (IVD) test carriers.
After one year of storage, the functionality of the primers and fluorophore-quencher combinations was validated
by real-time polymerase chain reaction (real-time PCR), confirming their stability when stored in the presence of
stabilizers, with the best results achieved using trehalose. This approach could be of great benefit for manufacturing
IVD systems, for example, for genotyping applications based on multiplexing using different fluorescent dyes. S. K. Vashist, E.M. Schneider, J.H.T. LuongSurface plasmon resonance-based immunoassay for human fetuin A 2014 Analyst , volume : 139, pages : 2237 - 2242» show abstract « hide abstract Abstract This article describes a highly-sensitive surface plasmon resonance (SPR)-based immunoassay (IA) for human fetuin A (HFA), a specific biomarker for atherosclerosis and hepatocellular carcinoma. The assay is based on a novel immobilization procedure that simply involves the dilution of an anti-HFA capture antibody (Ab) in 1% (v/v) 3-aminopropyltriethoxysilane (APTES), followed by its dispensing on a KOH-treated gold (Au)-coated SPR chip and incubation for 30 min. The developed SPR IA detected 0.3-20 ng mL(-1) of HFA with a limit of detection and sensitivity of 0.7 ng mL(-1) and 1 ng mL(-1), respectively. The highly-simplified Ab immobilization procedure is also 5-fold more rapid than conventional procedures. It leads to the leach-proof binding of the capture Ab, which means that the developed SPR IA is highly cost-effective, as the Ab-bound SPR chip could be reused for many repeated HFA IAs after regeneration with 10 mM glycine-HCl, pH 2.0. The Ab-bound SPR chip, stored at 4 °C, lost only 18% of its original activity after 4 months. For the detection of HFA spiked in diluted human whole blood and plasma, the results obtained by the developed SPR IA agreed well with the commercial HFA sandwich ELISA. A. Kloke, A. R. Fiebach, S. Zhang, L. Drechsel, S. Niekrawietz, M. Hoehl, R. Kneusel, K. Panthel, J. Steigert, F. von Stetten, R. Zengerle, N. PaustThe LabTube – A novel microfluidic platform for
assay automation in laboratory centrifuges 2014 Lab Chip , volume : 14, pages : 1527 - 1537» show abstract « hide abstract Abstract Assay automation is the key for successful transformation of modern biotechnology into
routine workflows. Yet, it requires considerable investment in processing devices and auxiliary
infrastructure, which is not cost-efficient for laboratories with low or medium sample
throughput or point-of-care testing. To close this gap, we present the LabTube platform, which
is based on assay specific disposable cartridges for processing in laboratory centrifuges.
LabTube cartridges comprise interfaces for sample loading and downstream applications and
fluidic unit operations for release of prestored reagents, mixing, and solid phase extraction.
Process control is achieved by a centrifugally-actuated ballpen mechanism. To demonstrate the
workflow and functionality of the LabTube platform, we show two LabTube automated sample
preparation assays from laboratory routine: DNA extractions from whole blood and
purification of His-tagged proteins. Equal DNA and protein yield were observed compared to
manual reference runs, while LabTube automation could significantly reduce the hands-ontime
to one minute per extraction. L. Zielke, T. Hutzenlaub, D. R. Wheeler, C.-W. Chao, I. Manke, A. Hilger, N. Paust, R. Zengerle, S. ThieleThree-Phase Multiscale Modeling of a LiCoO 2 Cathode:
Combining the Advantages of FIB–SEM Imaging and
X-Ray Tomography 2014 Adv Energy Mater , volume : 5, page : 1401612» show abstract « hide abstract Abstract LiCoO 2 electrodes contain three phases, or domains, each having specific-intended
functions: ion-conducting pore space, lithium-ion-reacting active
material, and electron conducting carbon-binder domain (CBD). Transport
processes take place in all domains on different characteristic length
scales: from the micrometer scale in the active material grains through to
the nanopores in the carbon-binder phase. Consequently, more than one
imaging approach must be utilized to obtain a hierarchical geometric representation
of the electrode. An approach incorporating information from the
micro- and nanoscale to calculate 3D transport-relevant properties in a largereconstructed
active domain is presented. Advantages of focused ion beam/
scanning electron microscopy imaging and X-ray tomography combined by
a spatial stochastic model, validated with an artifi cially produced reference
structure are used. This novel approach leads to signifi cantly different transport
relevant properties compared with previous tomographic approaches:
nanoporosity of the CBD leads to up to 42% additional contact area between
active material and pore space and increases ionic conduction by a factor
of up to 3.6. The results show that nanoporosity within the CBD cannot be
neglected. T. Hutzenlaub, S. Thiele, N. Paust, R. Spotnitz, R. Zengerle, C. WalchshoferThree-dimensional electrochemical Li-ion battery modelling featuring a focused ion-beam/scanning electron microscopy based three-phase reconstruction of a LiCoO2 cathode 2014 Electrochim Acta , volume : 115, pages : 131 - 139» show abstract « hide abstract Abstract We combine a three-phase, three-dimensional reconstruction of a LiCoO2battery cathode based onfocused ion-beam/scanning electron microscopy (FIB/SEM) imaging with an electrochemical model. Themodel considers the electric potential and lithium/salt concentration distribution in both the liquid elec-trolyte and the solid active-material phases. In contrast to previously presented models, we spatiallyresolve the carbon-binder phase to provide a more realistic description of the electric potential. Weobserve that carbon-binder coverage of the solid electrolyte interface (SEI) impedes local surface reac-tions and thus affects lithium redistribution. For the considered cathode, the total surface to volumeratio of the SEI is reduced from 11.2 × 105to 6.5 × 105m2m−3when the carbon-binder phase is modelledexplicitly. This leads to increased inhomogeneity of the lithium concentration in active-material grainsduring charging.Additionally, we study lithium/salt concentration in the electrolyte, revealing gradients between 0.9and 1.5 kmol m−3depending on the distance to the separator. This is significant because the lithium/saltconcentration directly affects the ion transport properties of the electrolyte. T. S. Santisteban, R. Zengerle, M. MeierThrough-holes, cavities and perforations in polydimethylsiloxane (PDMS) chips 2014 Rsc Adv , volume : 4, pages : 48012 - 48016» show abstract « hide abstract Abstract We present a method to fabricate through-holes between 10 to 180 µm between polydimethylsiloxane (PDMS) layers of microfluidic large-scale integration platforms. Therefore we employed standard PDMS spin-coating processes onto silicon molds with microstructures formed from SU-8 and AZ photoresists. Our approach is based on the modification of the surface polarity of the PDMS prototyping molds by a 250 nm thick layer of octafluorocyclobutane (C4F8), which resulted in a contact angle of 125 ± 3 degrees for water. This super hydrophobic surface repelled PDMS from microstructures protruding out of the spin coated PDMS layer. Subsequently, we applied and characterized the C4F8 coating for the robust fabrication of interlayer connectors between PDMS membranes of 40 µm thickness. To enable embedding of through-holes, perforations and/or cavities in very thin layers of PDMS (<20 µm) we mixed PDMS with inert silicone oil to reduce its viscosity. In difference to previous attempts to lower the viscosity of PDMS using organic solvents, the silicone oil cross-linked to PDMS and was thus, unable to freely diffuse into the polymerized PDMS. This reduces the risk for bleeding of hazardous components in biological applications. Finally, we manufactured a three layer mLSI chip with integrated cavities for catching fluorescently labeled beads and cells. The presented process parameters can easily be adapted to specific needs in fabrication of multi-layer PDMS arrangements by following the systematic parameter screening. L. Zielke, A. Fallisch, N. Paust, R. Zengerle, S. ThieleTomography based screening of flow field / current
collector combinations for PEM water electrolysis 2014 Rsc Adv , volume : 4, pages : 58888 - 58894» show abstract « hide abstract Abstract Current collectors in PEM water electrolysis perform several functions that influence overall performance. These include conducting heat and electrons, as well as transporting water and gas. X-ray tomography, standardized reconstruction, and calculation methods are used to compare the morphological and transport parameters of eight different current collectors functioning as flow fields for PEM water electrolysis. We find simple exponential relations between through-plane thermal conductivity l and porosity p (l20 C(p) ¼ 1749p 1.306 4.420), as well as between through-plane electrical conductivity s and water permeability K (s(K) ¼ 10 6 K 0.6376). In addition, we use both local and global concepts to investigate the pore space of current collectors. We hereby investigate homogeneity and characteristic sizes, like mean pore diameter or mean distance between solid parts at the catalytic interface. Moreover, we find that the local concept of mean chord lengths can be used to explain electrical and thermal conductivity anisotropies. These chords can be used to predict the direction of the largest conductivity for fibrous current collectors. S. Sané, K. Richter, S. Rubenwolf, N. J. Matschke, C. Jolivalt, C. Madzak, R. Zengerle, J. Gescher, S. KerzenmacherUsing planktonic microorganisms to supply the unpurified multi-copper oxidases
laccase and copper efflux oxidases at a biofuel cell cathode 2014 Bioresource Technol , volume : 158, pages : 231 - 238» show abstract « hide abstract Abstract The feasibility to apply crude culture supernatants that contain the multicopper oxidases
laccase or copper efflux oxidase (CueO) as oxygen reducing catalysts in a biofuel cell
cathode is shown. As enzyme-secreting recombinant planktonic microorganisms, the
yeast Yarrowia lipolytica and the bacterium Escherichia coli were investigated. The
cultivation and operation conditions (choice of medium, pH) had distinct effects on the
electro-catalytic performance. The highest current density of 119 ± 23 μAcm-2 at 0.400 V
vs. NHE was obtained with the crude culture supernatant of E. coli cells overexpressing
CueO and tested at pH 5.0. In comparison, at pH 7.4 the electrode potential at 100 μAcm-2
is 0.25 V lower. Laccase-containing supernatants of Y. lipolytica yielded a maximum
current density of 6.7 ± 0.4 μAcm-2 at 0.644 V vs. NHE. These results open future
possibilities to circumvent elaborate enzyme purification procedures and realize cost
effective and easy-to-operate enzymatic biofuel cells. back to the year overview S. Bammesberger, S. Kartmann, L. Tanguy, D. Liang, K. Mutschler, A. Ernst, R. Zengerle, P. KoltayA Low-Cost, Normally Closed, Solenoid Valve for Non-Contact Dispensing in the Sub-μL Range 2013 Micromachines , volume : 4, pages : 9 - 21» show abstract « hide abstract Abstract We present a disposable, normally closed, non-contact dispensing valve for the sub-μL range. The miniaturized solenoid valve (diameter: 8 mm, height: 27.25 mm) is compatible to standard Luer-Lock interfaces. A highly dynamic actuation principle enables opening times down to 1 ms. The dispensing performance was evaluated for water (η = 1.03 mPas) and a 66% (w/w) glycerol/water solution (η = 16.98 mPas), at pressures varying from 200 to 800 mbar. The experimentally determined minimal dispensing volume was 163 nL (CV 1.6%) for water and 123 nL (CV 4.5%) for 66% (w/w) glycerol/water. The low-cost polymer valve enables high precision dispensing of liquid volumes down to the lower end of the sub-μL range comparable to high-end non-disposable micro-dispensing valves. S. Bammesberger, I. Malki, A. Ernst, R. Zengerle, P. KoltayA calibration-free, noncontact, disposable liquid dispensing cartridge featuring an online process control 2013 Journal of Laboratory Automation , volume : 27, pages : 394 - 402» show abstract « hide abstract Abstract We present a noncontact liquid dispenser that uses a disposable cartridge for the calibration-free dosage of diverse biochemical reagents from the nanoliter to the microliter range. The dispensing system combines the advantages of a positive displacement syringe pump (responsible for defining the aliquot’s volume with high accuracy) with a highly dynamic noncontact dispenser (providing kinetic energy to detach the liquid from the tip). The disposable, noncontact dispensing cartridge system renders elaborate washing procedures of tips obsolete. A noncontact sensor monitors the dispensing process to enable an online process control. To further increase confidence and reliability for particularly critical biomedical applications, an optional closed-loop control prevents malfunctions. The dispensing performance was characterized experimentally in the range of 0.25 to 10.0 µL using liquids of different rheological properties (viscosity 1.03–16.98 mPas, surface tension 30.49–70.83 mN/m) without adjusting or calibrating the actuation parameters. The precision ranged between a coefficient of variation of 0.5% and 5.3%, and the accuracy was below ±10%. The presented technology has the potential to contribute significantly to the improvement of biochemical liquid handling for laboratory automation in terms of usability, miniaturization, cost reduction, and safety. Y. Abbas, J. Miwa, R. Zengerle, F. von StettenActive Continuous-Flow Micromixer Using an External Braille Pin Actuator Array 2013 Micromachines , volume : 4, pages : 80 - 89» show abstract « hide abstract Abstract We present a continuous-flow active micromixer based on channel-wall deflection in a polydimethylsiloxane (PDMS) chip for volume flows in the range up to 2 μL s−1 which is intended as a novel unit operation for the microfluidic Braille pin actuated platform. The chip design comprises a main microchannel connected to a series of side channels with dead ends aligned on the Braille pins. Computer-controlled deflection of the side-channel walls induces chaotic advection in the main-channel, which substantially accelerates mixing in low-Reynolds number flow. Sufficient mixing (mixing index MI below 0.1) of volume flows up to 0.5 μL s−1 could be achieved within residence times ~500 ms in the micromixer. As an application, continuous dilution of a yeast cell sample by a ratio down to 1:10 was successfully demonstrated. The mixer is intended to serve as a component of bio-analytical devices or as a unit operation in the microfluidic Braille pin actuated platform. S. Spieth, A. Schumacher, F. Trenkle, O. Brett, K. Seidl, S. Herwik, S. Kisban, P. Ruther, O. Paul, A. A. Aarts, H. P. Neves, P. D. Rich, D. E. Theobald, T. Holtzman, J. W. Dalley, B.-E. Verhoef, P. Janssen, R. ZengerleApproaches for drug delivery with intracortical probes 2013 Biomed Eng Online , volume : 59, issue : 4, pages : 291 - 303» show abstract « hide abstract Abstract Intracortical microprobes allow the precise monitoring of electrical and chemical signaling and are widely used in neuroscience. Microelectromechanical system (MEMS) technologies have greatly enhanced the integration of multifunctional probes by facilitating the combination of multiple recording electrodes and drug delivery channels in a single probe. Depending on the neuroscientific application, various assembly strategies are required in addition to the microprobe fabrication itself. This paper summarizes recent advances in the fabrication and assembly of micromachined silicon probes for drug delivery achieved within the EU-funded research project NeuroProbes. The described fabrication process combines a two-wafer silicon bonding process with deep reactive ion etching, wafer grinding, and thin film patterning and offers a maximum in design flexibility. By applying this process, three general comb-like microprobe designs featuring up to four 8-mm-long shafts, cross sections from 150×200 to 250×250 µm², and different electrode and fluidic channel configurations are realized. Furthermore, we discuss the development and application of different probe assemblies for acute, semichronic, and chronic applications, including comb and array assemblies, floating microprobe arrays, as well as the complete drug delivery system NeuroMedicator for small animal research. N. Wangler, M. Welsche, M. Blazek, M. Blessing, M. Vervliet-Scheebaum, R. Reski, C. Müller, H. Reinecke, J. Steigert, G. Roth, R. Zengerle, N. PaustBubble Jet agent release cartridge for chemical single cell
stimulation 2013 Biomed Microdevices , volume : 15, pages : 1 - 8» show abstract « hide abstract Abstract We present a new method for the distinct specific
chemical stimulation of single cells and small cell clusters
within their natural environment. By single-drop release of
chemical agents with droplets in size of typical cell diameters
(d <30 μm) on-demand micro gradients can be generated
for the specific manipulation of single cells. A single
channel and a double channel agent release cartridge with
integrated fluidic structures and integrated agent reservoirs
are shown, tested, and compared in this publication. The
single channel setup features a fluidic structure fabricated by
anisotropic etching of silicon. To allow for simultaneous
release of different agents even though maintaining the same
device size, the second type comprises a double channel
fluidic structure, fabricated by photolithographic patterning
of TMMF. Dispensed droplet volumes are V015 pl and V0
10 pl for the silicon and the TMMF based setups, respectively.
Utilizing the agent release cartridges, the application in biological
assays was demonstrated by hormone-stimulated premature
bud formation in Physcomitrella patens and the
individual staining of one single L 929 cell within a confluent
grown cell culture. O. Strohmeier, A. Emperle, G. Roth, D. Mark, R. Zengerle, F. von StettenCentrifugal gas-phase transition magnetophoresis (GTM) – a generic method for automation of magnetic bead based assays on the centrifugal microfluidic platform and application to DNA purification 2013 Lab Chip (Lab On A Chip) 2013 , volume : 13, pages : 146 - 155» show abstract « hide abstract Abstract Transportation of magnetic beads between different reagents plays a crucial role in many biological assays
e.g. for purification of biomolecules or cells where the beads act as a mobile solid support. Therefore,
usually a complex set-up either for fluidic processing or for manipulation of magnetic beads is required. To
circumvent these drawbacks, we present a facile and automated method for the transportation of
magnetic beads between multiple microfluidic chambers on a centrifugal microfluidic cartridge ‘‘LabDisk’’.
The method excels by requiring only one stack of stationary permanent magnets, a specific microfluidic
layout without actively controlled valves and a predefined frequency protocol for rotation of the LabDisk.
Magnetic beads were transported through three fluidically separated chambers with a yield of 82.6% ¡
3.6%. Bead based DNA purification from a dilution series of a Listeria innocua lysate and from a lambda
phage DNA standard was demonstrated where the three chambers were used for binding, washing and
elution of DNA. Recovery of L. innocua DNA was up to 68% ¡ 24% and for lambda phage DNA 43% ¡
10% compared to manual reference purification in test tubes. Complete purification was conducted
automatically within 12.5 min. Since all reagents can be preloaded onto the LabDisk prior to purification,
no further hands-on steps are required during processing. Due to its modular and generic character, the
presented method could also be adapted to other magnetic bead based assays e.g. to immunoassays or
protein affinity purification, solely requiring the adjustment of number and volumes of the fluidic
chambers. D. Mark, F. von Stetten, R. ZengerleChips with everything: microfluidics and diagnostics 2013 Medical Device Developments N. Lass, L. Riegger, R. Zengerle, P. KoltayEnhanced Liquid Metal Micro Droplet Generation
by Pneumatic Actuation Based on the StarJet Method 2013 Micromachines , volume : 4, pages : 49 - 66» show abstract « hide abstract Abstract We present a novel pneumatic actuation system for generation of liquid metal
droplets according to the so-called StarJet method. In contrast to our previous work, the
performance of the device has been significantly improved: the maximum droplet
generation frequency in continuous mode has been increased to fmax = 11 kHz (formerly
fmax = 4 kHz). In addition, the droplet diameter has been reduced to 60 μm. Therefore, a
new fabrication process for the silicon nozzle chips has been developed enabling the
production of smaller nozzle chips with higher surface quality. The size of the metal
reservoir has been increased to hold up to 22 mL liquid metal and the performance and
durability of the actuator has been improved by using stainless steel and a second
pneumatic connection to control the sheath flow. Experimental results are presented
regarding the characterization of the droplet generation, as well as printed metal structures. T. Hutzenlaub, A. Asthana, J. Becker, R. Wheeler, R. Zengerle, S. ThieleFIB/SEM-based calculation of tortuosity in a porous LiCoO2 cathode for a Li-ion battery 2013 Electrochem Commun , volume : 27, pages : 77 - 80» show abstract « hide abstract Abstract We present a new method to quantify tortuosity in the porous, LiCoO2 cathode of a Li-ion battery. The
starting point is a previously published 3D reconstruction from FIB/SEM images with three phases, the active
material domain, carbon-binder domain and pore space. Based on this geometrical configuration, we compute
effective diffusivities, from which we in turn derive tortuosity values for the pore space ranging between
5 and 11.6 for the three spatial directions. In a next step, we compare our approach to an imaging method
that employs back-filling material. These methods do not differentiate between the carbon-binder domain
and the pore space. Thus we remove the carbon-binder domain from our 3D reconstruction and add its
volume to the pore space. As a result of this procedure, the tortuosity is greatly reduced to values between
1.5 and 1.9. Experiments suggest that both results for tortuosity are inaccurate and that the real values lie
somewhere between these parameter sets. Hence, based on experimental data, we propose a nanoporous
carbon-binder domain and derive intermediate tortuosity values between 4.2 and 6.1. These values are consistent
with experimental values for similar Li-ion cathodes reported previously. A. Kloke, C. Köhler, A. Dryzga, R. Gerwig, K. Schumann, M. Ade, R. Zengerle, S. KerzenmacherFabrication of Highly Porous Platinum by Cyclic Electrodeposition of PtCu Alloys: How do Process Parameters Affect Morphology? 2013 J Electrochem Soc , volume : 160, issue : 2, pages : D111 - D118» show abstract « hide abstract Abstract In this work we analyze the influence of process parameters on the morphology of highly porous platinum electrodes, fabricated by co-deposition of platinum-copper alloy and subsequent selective dissolution of the less noble copper during multiple cyclic voltammetry scans. Thereto the Cu2+ concentration in the deposition electrolyte, the negative scan limit, and the scan rate were varied. Corresponding electrodes were characterized by their surface texture (scanning electron microscopy, X-ray diffractometry), specific surface area, and elemental compositions (X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy). Under conditions enforcing precursor depletion a sphere-dominated structure is observed, whereas oppositional configurations lead to smoother, mud-crack pattern like structures. Electrodes of high specific surface area are obtained particularly when high copper ion concentrations (100 mmol l−1 CuSO4, roughness factor 3740 ± 270), high negative scan limits (−0.800 V vs. SCE, roughness factor 3790 ± 370) and low scan speeds (1 mV s−1, roughness factor 3930 ± 370) compared to standard parameters (20 mmol l−1 CuSO4, −0.600 V vs. SCE negative scan limit, 1 mV s−1, roughness factor 3040 ± 300) were applied during fabrication. Since the fabrication of these highly rough electrodes requires the deposition of high amounts of platinum (10–20 mg per cm2 footprint area) it is mainly relevant to applications such as neurostimulation electrodes or implantable glucose fuel cells in which platinum costs are less relevant than electrode properties and functionality. C. Köhler, A. Kloke, A. Drzyzga, R. Zengerle, S. KerzenmacherFabrication of highly porous platinum electrodes for micro-scale applications by pulsed electrodeposition and dealloying 2013 Journal of Power Sources , volume : 242, pages : 255 - 263» show abstract « hide abstract Abstract We present the implementation and optimization of a novel electrodeposition method for the fabrication of highly porous platinum electrodes. It is based on the co-deposition of platinum and copper and the selective dealloying of copper in a pulsed manner. The new process yields mechanically stable platinum electrodes with roughness factors of up to RF = 6500 ± 700, compared to the state-of-the-art cyclic electrodeposition method this corresponds to an improvement in RF by 111 %. Furthermore the time demand for fabrication is reduced by 59 %, whereas the platinum utilization is increased by 53 %. The method is particularly advantageous for applications such as micro fuel cells since it enables the precise deposition of catalytically active electrodes on micro-structured conductive areas. In this context the novel platinum electrodes show higher current densities for the oxidation of formic acid and glucose than state-of-the-art electrodes. In terms of methanol oxidation their catalytic activity is comparable to commercial direct methanol fuel cell (DMFC) electrodes, fabricated from Pt-Ru nanoparticles dispersed on carbon black. T. Hutzenlaub, J. Becker, R. Zengerle, S. ThieleHow Coarsening the 3D Reconstruction of a Porous Material Influences Diffusivity and Conductivity Values 2013 ECS Electrochemistry Letters , volume : 2, pages : F14 - F17» show abstract « hide abstract Abstract Coarsening the resolution of a 3D reconstruction is a common approach to make simulations feasible with regard to computational
resources. We coarsen the reconstruction of a PEMFC cathode catalyst layer and investigate how this influences parameters such as
diffusivity and conductivity. This is also an indication of how trustworthy these parameters are in the first place, because imaging
itself is a coarsened representation of the real morphology. While diffusivity remains approximately constant due to the opposing
behavior of bulk and Knudsen diffusivity, conductivity is strongly affected. The method introduced here is transferable to evaluate
3D reconstructions of other porous materials. T. Brettschneider, C. Dorrer, D. Czurratis, R. Zengerle, M. DaubLaser micromachining as a metallization tool for microfluidic polymer stacks 2013 J Micromech Microeng , volume : 23, pages : 035020 - 035030» show abstract « hide abstract Abstract A novel assembly approach for the integration of metal structures into polymeric microfluidic systems is described. The presented production process is completely based on a single solid-state laser source, which is used to incorporate metal foils into a polymeric multi-layer
stack by laser bonding and ablation processes. Chemical reagents or glues are not required.
The polymer stack contains a flexible membrane which can be used for realizing microfluidic valves and pumps. The metal-to-polymer bond was investigated for different metal foils and plasma treatments, yielding a maximum peel strength of Rps = 1.33N mm−1. A minimum structure size of 10 μm was determined by 3D microscopy of the laser cut line. As an example application, two different metal foils were used in combination to micromachine a standardized type-T thermocouple on a polymer substrate. An additional laser process was developed which allows metal-to-metal welding in close vicinity to the polymer substrate.
With this process step, the reliability of the electrical contact could be increased to survive at least 400 PCR temperature cycles at very low contact resistances. C. Cupelli, T. Borchardt, T. Steiner, N. Paust, R. Zengerle, M. SanterLeukocyte enrichment based on a modified pinched flow
fractionation approach 2013 Microfluid Nanofluid , volume : 14, issue : 3-4, pages : 551 - 563» show abstract « hide abstract Abstract In this paper, a simple and robust design for a
passive hydrodynamic cell sorter based on pinched flow-field
fractionation is presented and analyzed. Two principal layouts
of the sorter are discussed and investigated experimentally
as well as numerically based on the dissipative particle
dynamics (DPD) method. Experimentally, design 1 approximately
sorts 87 % of the erythrocytes to their designated
outlet, while 100 % of the leukocytes branch correctly. This
also holds for design 2 differing merely in the direction of the
outlet for erythrocytes, but here only 69 % of the red blood
cells are redirected to the designated outlet. This behavior
can be elucidated by employing DPD simulations, where
erythrocytes advected with the flow are modeled explicitly.
Our results suggest that if a cell sorter is designed to operate
at high throughput, its layout may not entirely rely on commonly
assumed idealizing conditions, because cells cannot
be considered as point-like, isolated objects following definite
stream lines. Hydrodynamic forces originating from the
cells as extended objects must be taken into account. T. van Oordt, Y. Barb, J. Smetana, R. Zengerle, F. von StettenMiniature stick-packaging – an industrial technology for
pre-storage and release of reagents in lab-on-a-chip
systems 2013 Lab Chip , volume : 13, issue : 15, pages : 2888 - 2892» show abstract « hide abstract Abstract Stick-packaging of goods in tubular-shaped composite-foil pouches has become a popular technology for
food and drug packaging. We miniaturized stick-packaging for use in lab-on-a-chip (LOAC) systems to prestore
and on-demand release the liquid and dry reagents in a volume range of 80–500 ml. An integrated
frangible seal enables the pressure-controlled release of reagents and simplifies the layout of LOAC
systems, thereby making the package a functional microfluidic release unit. The frangible seal is adjusted
to defined burst pressures ranging from 20 to 140 kPa. The applied ultrasonic welding process allows the
packaging of temperature sensitive reagents. Stick-packs have been successfully tested applying recovery
tests (where 99% (STDV = 1%) of 250 ml pre-stored liquid is released), long-term storage tests (where there
is loss of only ,0.5% for simulated 2 years) and air transport simulation tests. The developed technology
enables the storage of a combination of liquid and dry reagents. It is a scalable technology suitable for
rapid prototyping and low-cost mass production. D. Trebbels, A. Kern, F. Fellhauer, C. Huebner, R. ZengerleMiniaturized FPGA-Based High-Resolution
Time-Domain Reflectometer 2013 Ieee , volume : 62, issue : 7, pages : 2101 - 2113» show abstract « hide abstract Abstract Time-domain reflectometry (TDR) is a well-known
measurement principle for evaluating frequency-dependent electric
and dielectric properties of various materials and substances.
Although TDR is a proven method, the high price for TDR
measurement equipment and complex laboratory setups is often
a limiting factor for cost-sensitive applications or large-scale field
experiments, where a large number of TDR meters is required.
This paper reports on the development of a new miniaturized
low-cost TDR meter capable of sampling a repetitive rectangular
waveform, which is used as an excitation signal. The developed
sampling circuit is based on a digital delta modulator (DM) and
allows for capturing the waveform of a repetitive measurement
signal. A 1-MHz signal can be captured with a virtual sampling
resolution of 1 ps within a measurement interval of 1 s. The
generated pulses have a rise time of 2 ns and can be captured with
an amplitude resolution of approximately 10 bit and an accuracy
of approximately 8 bit. The developed digital DM architecture is
implemented inside a small field programmable gate array and
integrated into a miniaturized low-power TDR meter prototype
for battery-powered outdoor applications. The captured measurement
data are stored on integrated micro-SD card memory and
can be read out either via a Universal Serial Bus, an RS-485 bus
system, or a wireless interface. The TDR meter is controlled by an
integrated microcontroller and a real-time clock and therefore can
operate completely independent from any additional control setup.
The TDR meter targets applications within the field of geoscience
and agricultural monitoring, where large-scale measurement systems
are required. N. Losleben, J. Spinke, S. Adler, N. Oranth, R. ZengerleModel fluids representing aqueous in-vitro diagnostic reagents for the development of dispensing systems 2013 Drug Discov Today , pages : 1035 - 1042» show abstract « hide abstract Abstract Analyzers for in-vitro diagnostic (IVD) testing facilitate the determination of medical information from
biological samples. To reach a high quality, the detection reagents have to be dispensed with a high
degree of precision and accuracy. A technology change from conventional pipetting systems to contactfree
dispensers provides the opportunity to reduce carry-over and handle reagents in the microliter
range. A great challenge for the development and validation of new systems is the huge variety of the IVD
reagents. This work presents the fluidic properties of 646 different aqueous IVD reagents and how they
can be represented by a set of easy-to-prepare model fluids, covering the rheological range of the
reagents. In addition, based on the model fluids, a standardized approach is presented for the evaluation
of dispensers for IVD applications. T. Hutzenlaub, J. Becker, R. Zengerle, S. ThieleModelling the water distribution within a hydrophilic and hydrophobic 3D reconstructed cathode catalyst layer of a proton exchange membrane fuel cell 2013 J Power Sources , volume : 227, pages : 260 - 266» show abstract « hide abstract Abstract We reconstruct a section of the cathode catalyst layer (CCL) of a Gore PEMFC membrane electrode
assembly three-dimensionally with nanometre scale resolution. Subsequently, we present a new
modelling method to fill the pore space of this matrix stepwise with water, enabling the description of
varying saturation conditions of the CCL. The method is based on a 3D pore size distribution and enables
to differentiate between a hydrophilic and a hydrophobic CCL. It utilizes a sequence to fill the pores
according to their size, going from small to large (hydrophilic) or vice versa (hydrophobic), until a predefined
value of water saturation is reached. We compare both cases by calculating an effective diffusivity
for oxygen in nitrogen in all spatial directions. Both the hydrophilic and the hydrophobic case
display a similar ability to transport oxygen up to approximately 50% water saturation of the pore space.
At higher water saturation, we calculate larger diffusivity values for the hydrophobic case. Finally, we
calculate the specific reaction surface area that is accessible from the gas diffusion layer via unfilled pores
for all water saturation conditions. At 50% saturation, the hydrophobic case displays a twenty times
larger reaction surface area than the hydrophilic case. O. Strohmeier, S. Laßmann, B. Riedel, D. Mark, G. Roth, M. Werner, R. Zengerle, F. von StettenMultiplex genotyping of KRAS point mutations in tumor cell DNA by allele-specific real-time PCR on a centrifugal microfluidic disk segment 2013 Microchim Acta , volume : 181, pages : 1681 - 1688» show abstract « hide abstract Abstract Point Mutations on the Kirsten rat sarcoma viral oncogene homolog (KRAS) have been identified as an important predictive biomarker for response to cancer therapy targeting the epidermal growth factor receptor. KRAS mutations are prevalent in up to 40 % of all colorectal carcinomas, and routinely conducted KRAS genotyping is becoming mandatory to predict therapy success and to reduce therapy costs. We report a low-cost, disposable and ready-to-use centrifugal microfluidic cartridge (termed GeneSlice) containing preloaded primers and probes. The GeneSlice cartridge enables the parallel detection of the seven most relevant KRAS point mutations by allele-specific real-time PCR. It represents a cost effective alternative to dideoxy-sequencing with a faster time-to-result (~ 2 h versus up to 20 h in case of dd-sequencing). Microfluidic processing of the GeneSlice along with allele-specific amplification and real-time detection are conducted in a slightly modified, commercially available PCR thermocycler. Intra-chip standard deviation of Cq values on the GeneSlices is negligible (GeneSlice 1: Cq,std.dev. = 0.13; GeneSlice 2: Cq,std.dev = 0.26). In 23 of 24 experiments, the data for genotyping 6 cancer cell lines (n = 4 per cell line) agreed with dd-sequencing. Additionally, DNA derived from microdissected formalin-fixed and paraffin embedded colorectal carcinomas of two cases was genotyped correctly and reproducibly (n = 3 per patient; one GeneSlice excluded from evaluation). The GeneSlice therefore clearly demonstrated the potential to become a valuable tool for routine diagnostics of KRAS mutations by reducing costs and hands-on time. S. Thiele, T. Fürstenhaupt, D. Banham, T. Hutzenlaub, V. Birss, C. Ziegler, R. ZengerleMultiscale tomography of nanoporous carbon-supported noble metal catalyst layers 2013 J Power Sources , volume : 228, pages : 185 - 192» show abstract « hide abstract Abstract Noble metal catalysts are a scarce, non-renewable resource, and yet are required in a wide range of industrial applications, including in polymer electrolyte membrane fuel cells (PEMFCs). The effectiveness of PEMFCs depends not only on the size, active surface area, and distribution of the Pt catalyst nanoparticles, which affects reaction kinetics, but also on the porous structure of the carbon support, which affects mass transport. Unfortunately, the very different size scales – several nm for the Pt catalyst vs. several μm for the porosity features – cannot be characterized by a single method. Here, we present a novel approach for integrating information from both of these size scales to build a single geometrical model. Focused Ion Beam – Scanning Electron Microscope tomography (SEMt) was carried out on a commercial PEMFC cathode catalyst layer to characterize porosity, connectivity as well as pore-size and grain-size distribution. Transmission Electron Microscopy tomography (TEMt) was used to analyze volume and surface area distributions of nanometer sized platinum catalyst particles. Further, we propose an up-scaling approach to translate the information obtained from TEMt to SEMt. Knowledge of catalyst particle locations within the solid support matrix will be critical in enabling the analysis of limiting transport processes in PEMFC CCLs. D. Liang, C. Steinert, S. Bammesberger, L. Tanguy, A. Ernst, R. Zengerle, P. KoltayNovel gravimetric measurement technique for quantitative volume calibration in the sub-microliter range 2013 Meas Sci Technol , volume : 24, pages : 025301 - 025311» show abstract « hide abstract Abstract We present a novel measurement method based on the gravimetric principles adapted from the ASTM E542 and ISO 4787 standards for quantitative volume determination in the
sub-microliter range. Such a method is particularly important for the calibration of non-contact micro dispensers as well as other microfluidic devices. The novel method is based on the linear regression analysis of continuously monitored gravimetric results and therefore is referred to as ‘gravimetric regression method (GRM)’. In this context, the regression analysis is necessary
to compensate the mass loss due to evaporation that is significant for very small dispensing volumes. A full assessment of the measurement uncertainty of GRM is presented and results in a standard measurement uncertainty around 6 nl for dosage volumes in the range from 40 nl to
1 μl. The GRM has been experimentally benchmarked with a dual-dye ratiometric photometric method (Artel Inc., Westbrook, ME, USA), which can provide traceability of
measurement to the International System of Units (SI) through reference standards maintained by NIST. Good precision (max. CV = 2.8%) and consistency (bias around 7 nl in the volume range from 40 to 400 nl) have been observed comparing the two methods. Based on the ASTM and ISO standards on the one hand and the benchmark with the photometric method on the other hand, two different approaches for establishing traceability for the GRM are discussed. S. Sané, C. Jolivalt, G. Mittler, P. Nielsen, S. Rubenwolf, R. Zengerle, S. KerzenmacherOvercoming Bottlenecks of Enzymatic Biofuel Cell Cathodes: Crude Fungal Culture Supernatant Can Help to Extend Lifetime and Reduce Cost 2013 ChemSusChem , volume : 6, issue : 7, pages : 1209 - 1215» show abstract « hide abstract Abstract Enzymatic biofuel cells (BFCs) show great potential for the direct conversion of biochemically stored energy from renewable biomass resources into electricity. However, enzyme purification is time-consuming and expensive. Furthermore, the long-term use of enzymatic BFCs is hindered by enzyme degradation, which limits their lifetime to only a few weeks. We show, for the first time, that crude culture supernatant from enzyme-secreting microorganisms (Trametes versicolor) can be used without further treatment to supply the enzyme laccase to the cathode of a mediatorless BFC. Polarization curves show that there is no significant difference in the cathode performance when using crude supernatant that contains laccase compared to purified laccase in culture medium or buffer solution. Furthermore, we demonstrate that the oxygen reduction activity of this enzymatic cathode can be sustained over a period of at least 120 days by periodic resupply of crude culture supernatant. This is more than five times longer than control cathodes without the resupply of culture supernatant. During the operation period of 120 days, no progressive loss of potential is observed, which suggests that significantly longer lifetimes than shown in this work may be possible. Our results demonstrate the possibility to establish simple, cost efficient, and mediatorless enzymatic BFC cathodes that do not require expensive enzyme purification procedures. Furthermore, they show the feasibility of an enzymatic BFC with an extended lifetime, in which self-replicating microorganisms provide the electrode with catalytically active enzymes in a continuous or periodic manner. M. Blazek, C. Betz, M. N. Hall, M. Reth, R. Zengerle, M. MeierProximity Ligation Assay for High Content Profiling of Cell Signaling Pathways on a Microfluidic Chip 2013 Mol Cell Proteomics , volume : 12, issue : 12, pages : 3898 - 3907» show abstract « hide abstract Abstract Here, we present the full integration of a proximity ligation assay (PLA) on a
microfluidic chip for systematic cell signaling studies. PLA is an in situ technology for detection
of protein interaction, post-translational modification, concentration, and cellular location with
single molecule resolution. Analytical performance advances on chip are achieved, including full
automation of the biochemical PLA steps, target multiplexing, and reduction of antibody
consumption by two orders of magnitudes compared to standard procedures. In combination with
a microfluidic cell-culturing platform, control over 128 cell culture microenvironments is gained.
We demonstrate the use of the combined cell-culture and protein analytic assay on chip by
characterizing the Akt signaling pathway upon PDGF stimulation. Signal transduction is detected
by monitoring the phosphorylation state of Akt, GSK-3β, p70S6K, S6, Erk1/2, mTOR, and the
cellular location of FoxO3a in parallel with the PLA. Single-cell PLA results revealed for Akt
and direct targets of Akt a maximum activation time of 4–8 min upon PDGF stimulation.
Activation times for phosphorylation events downwards in the Akt signaling pathway including
phosphorylation of S6, p70S6K, and mTOR are delayed by 8–10 min or exhibit a response time
of at least 1 h. Quantitative confirmation of the Akt phosphorylation signal was determined with
the help of a mouse embryonic fibroblast cell line (MEF) deficient for rictor. Taken together, the
miniaturized PLA chip establishes a biotechnological tool for general cell signaling studies and
their dynamics relevant for a broad range of biological inquiry. S. Bammesberger, A. Ernst, N. Losleben, L. Tanguy, R. Zengerle, P. KoltayQuantitative characterization of non-contact microdispensing technologies for the sub-microliter range 2013 Drug Discov Today , volume : 18, issue : 9-10, pages : 435 - 446» show abstract « hide abstract Abstract This work describes how to effectively compare non-contact dispensing technologies for automated liquid handling under high-throughput screening (HTS) conditions in the range of 0.05–10 ml. Exemplarily, we characterize five established technologies and categorize them into valve-based and positive displacement-based technologies. Furthermore we introduce dispensing accuracy and precision in an ‘intrarun’, ‘inter-run’ and ‘tip-to-tip’ context as universally applicable performance parameters. A NIST traceable spectrophotometric measurement method is utilized for experimental characterization. It yields an Intra-Run CV (Inter-Run CV) between 0.4% to 7.7% (0.5 to 10.9%)
and a Tip-to-Tip CV between 1.4% and 9.9% for target volumes <1 ml. An absolute accuracy of better than 5.0% is generally difficult to achieve in the sub-microliter range. T. van Oordt, G. B. Stevens, S. K. Vashist, R. Zengerle, F. von StettenRapid and highly sensitive luciferase reporter assay for the automated detection of botulinum toxin in the centrifugal microfluidic LabDisk platform 2013 Rsc Adv , volume : 3, pages : 22046 - 22052» show abstract « hide abstract Abstract We developed a system for the detection of botulinum neurotoxin (BoNT) type A based on a highly sensitive luciferase reporter assay automated by the centrifugal microfluidic LabDisk platform. The assay is based on the detection of BoNT's proteolytic activity and generation of a bioluminescent signal due to the release of firefly luciferase, pre-bound to microbeads via a cleavable peptide linker, in response to BoNT. It detected purified BoNT, BoNT in complex with neurotoxin associated proteins, and the recombinant enzymatic BoNT light chain in buffer and whole milk in the concentration range of 8 pM to 6 nM with an analytical sensitivity and limit of detection of 10–39 pM and 6–14 pM, respectively. The intra-disk, intra-day and inter-day variability were in the range of 1–13%, 1–7% and 10–13%, respectively. The developed assay correlated well with the conventional microwell plate assay. It is superior to the conventional BoNT assays in terms of portability, cost-effectiveness, lesser sample requirement, lesser number of steps and detection of a broad spectrum of BoNT serotypes and subtypes. It takes only 30 minutes, which is ideal for point-of-need BoNT detection in the case of security threats and food monitoring. K. G. Kraiczek, G. P. Rozing, R. ZengerleRelation between chromatographic resolution and signal-to-noise ratio in spectrophotometric HPLC detection 2013 Anal Chem , volume : 85, pages : 4829 - 4835» show abstract « hide abstract Abstract Absorption spectrophotometry has been and still is the
industry standard for detection in HPLC. Limit of detection (LOD)
and linear dynamic range (LDR) are the primary performance requirements
and have driven continuous improvement of spectrophotometric HPLC
detectors. Recent advances in HPLC column technology have led to low
flow-rate HPLC such as capillary HPLC and nanoflow HPLC and put
higher demands on optical HPLC signal detection. However, fundamental
principles in spectrophotometric HPLC detection have not been reviewed
for many years. In particular the relationship between the detector’s signalto-
noise ratio (SNR) and band broadening needs to be re-evaluated. In this
work, a new quantitative model is presented which allows the calculation of
the trade-off made between chromatographic resolution and SNR in
spectrophotometric HPLC detection. Modern optics flow cells based on
total internal reflection are included and compared to conventional flow cells. K. Kliche, G. Kattinger, S. Billat, L. Shen, S. Messner, R. ZengerleSensor for thermal gas analysis based on micromachined silicon-microwires 2013 Ieee Sens J , volume : 13, issue : 7, pages : 2626 - 2635» show abstract « hide abstract Abstract We present a microelectromechanical systems-based
sensor for the thermal detection of changes of gas mixtures
such as the CO2 concentration in air that is of interest in air
conditioning climate control within buildings. Key properties of
the system are low power consumption (<10 mW) and high longterm
stability through the absence of moving or consumptive
components. The used sensor chip has three silicon-microwires
(thermistors) surrounded by the gas mixture to be analyzed.
A centered wire (heater) is supplied with sinusoidal heating
power. This induces a thermal response via the surrounding gas to
measurement wires (detectors) located in different distances from
the heater. The phase shift between heating power and induced
thermal responses at the detectors is analyzed and depends on
the thermal properties of the gas. After calibration, the sensor
is able to quantify the concentration of an individual component
within a mixture of different but known gas components. This is
demonstrated by measuring the CO2 concentration in N2/CO2
mixtures with a resolution of 0.2% at constant pressure and
temperature. A. Gross, J. Schöndube, S. Niekrawitz, W. Streule, L. Riegger, R. Zengerle, P. KoltaySingle-Cell Printer: Automated,On Demand, and Label Free 2013 JALA - J Lab Autom , volume : 18, issue : 6, pages : 504 - 518» show abstract « hide abstract Abstract Within the past years, single-cell analysis has developed into a key topic in cell biology to study cellular functions that are
not accessible by investigation of larger cell populations. Engineering approaches aiming to access single cells to extract
information about their physiology, phenotype, and genotype at the single-cell level are going manifold ways, meanwhile
allowing separation, sorting, culturing, and analysis of individual cells. Based on our earlier research toward inkjet-like
printing of single cells, this article presents further characterization results obtained with a fully automated prototype
instrument for printing of single living cells in a noncontact inkjet-like manner. The presented technology is based on a
transparent microfluidic drop-on-demand dispenser chip coupled with a camera-assisted automatic detection system. Cells
inside the chip are detected and classified with this detection system before they are expelled from the nozzle confined in
microdroplets, thus enabling a “one cell per droplet” printing mode. To demonstrate the prototype instrument’s suitability
for biological and biomedical applications, basic experiments such as printing of single-bead and cell arrays as well as
deposition and culture of single cells in microwell plates are presented. Printing efficiencies greater than 80% and viability
rates about 90% were achieved. E. Kipf, J. Koch, B. Geiger, J. Erben, K. Richter, J. Gescher, R. Zengerle, S. KerzenmacherSystematic screening of carbon-based anode materials for microbial fuel cells with Shewanella oneidensis MR-1 2013 Bioresource Technol , volume : 146, pages : 386 - 329» show abstract « hide abstract Abstract We present a systematic screening of carbon-based anode materials for microbial fuel cells with Shewanella oneidensis MR-1. Under anoxic conditions nanoporous activated carbon cloth is a superior anode material in terms of current density normalized to the projected anode area and anode volume (24.0 ± 0.3 μA cm−2 and 482 ± 7 μA cm−3 at −0.2 vs. SCE, respectively). The good performance can be attributed to the high specific surface area of the material, which is available for mediated electron transfer through self-secreted flavins. Under aerated conditions no influence of the specific surface area is observed, which we attribute to a shift from primary indirect electron transfer by mediators to direct electron transfer via adherent cells. Furthermore, we show that an aerated initial growth phase enhances the current density under subsequent anoxic conditions fivefold when compared to a similar experiment that was conducted under permanently anoxic conditions. T. Brettschneider, C. Dorrer, M. Bründel, R. Zengerle, M. DaubWafer-level packaging and laser bonding as an approach for silicon-into-lab-on-chip integration 2013 J. Micromech. Microeng. , volume : 23, pages : 055005 - 055014» show abstract « hide abstract Abstract A novel approach for the integration of silicon biosensors into microfluidics is presented. Our approach is based on wafer-level packaging of the silicon die and a laser-bonding process of the resulting mold package into a polymer-multilayer stack. The introduction of a flexible and 40 μm thin hot melt foil as an intermediate layer enables laser bonding between materials with different melting temperatures, where standard laser welding processes cannot be employed. All process steps are suitable for mass production, e.g. the approach does not involve any dispensing steps for glue or underfiller. The integration approach was demonstrated and evaluated regarding process technology by wafer-level redistribution of daisy chain silicon dies representing a generic biosensor. Electrical connection was successfully established and laser-bonding tensile strength of 5.7 N mm−2 and burst pressure of 587 kPa at a temperature of 100 °C were achieved for the new material combination. The feasibility of the complete packaging approach was shown by the fabrication of a microfluidic flow cell with embedded mold package. back to the year overview Vosseler M, Clemenz M, Zengerle RA flat and cost effective actuator based on
superabsorbent polymer driving a skin
attachable drug delivery system 2012 Smart Materials and Structures , volume : 21, pages : 105002 - 105013» show abstract « hide abstract Abstract We present a flat and cost effective volume displacement actuator based on superabsorbent polymer. It offers slow kinetics and is able to work against reasonable back-pressures,e.g. 0.50 ml in 235 min at 140 kPa. It is predestined for low-cost skin attachable drug delivery
devices. The actuator consists of a plastic ring filled with superabsorbent polymer granulate. It is sealed with a thermoplastic elastomeric membrane on one side and a stiff filter membrane on the other side. After adding a defined amount (e.g. 2 or 10 ml) of swelling agent the
actuator shows a fast initial volume displacement within a few minutes followed by a slow continuous increase of this volume within hours. Minimized initial volume displacement and maximized displaced volume after 4 h cannot be combined in one actuator. A minimized initial displacement can be as low as 0.10 ml +/- 0.03 ml. A maximized displaced volume after 4 h can be 1.71 ml +/- 0.18 ml, not considering the initial effect. The back-pressure dependency
of one selected actuator design was studied. At a back-pressure of 100 kPa the displaced volume is reduced by 33%. We investigated various actuator designs with varying surface area, hardness of the elastomeric membrane and superabsorbent polymer. Finally, we demonstrate a skin attachable drug delivery system based on the employment of the superabsorbent polymer actuator. M Kunze, J Merz, W-J Hummel, H Glosch, S Messner, R ZengerleA micro dew point sensor with a thermal detection principle 2012 Meas Sci Technol , volume : 23, pages : 014004 - (10pp)» show abstract « hide abstract Abstract We present a dew point temperature sensor with the thermal detection of condensed water on a
thin membrane, fabricated by silicon micromachining. The membrane (600 × 600×∼1 μm3)
is part of a silicon chip and contains a heating element as well as a thermopile for temperature
measurement. By dynamically heating the membrane and simultaneously analyzing the
transient increase of its temperature it is detected whether condensed water is on the
membrane or not. To cool the membrane down, a peltier cooler is used and electronically
controlled in a way that the temperature of the membrane is constantly held at a value where
condensation of water begins. This temperature is measured and output as dew point
temperature. The sensor system works in a wide range of dew point temperatures between 1 K
and down to 44 K below air temperature. In experimental investigations it could be proven that
the deviation of the measured dew point temperatures compared to reference values is below
±0.2 K in an air temperature range of 22 to 70 ◦C. At low dew point temperatures of −20 ◦C
(air temperature = 22 ◦C) the deviation increases to nearly −1 K. S. Spieth, A. Schumacher, T. Holtzman, P. D. Rich, D. E. Theobald, J. W. Dalley, R. Nouna, S. Messner, R. ZengerleAn intra-cerebral drug delivery system for freely
moving animals 2012 Biomed Microdevices , volume : 14, pages : 799 - 809» show abstract « hide abstract Abstract Microinfusions of drugs directly into the central
nervous system of awake animals represent a widely used
means of unravelling brain functions related to behaviour.
However, current approaches generally use tethered liquid
infusion systems and a syringe pump to deliver drugs into
the brain, which often interfere with behaviour. We address
this shortfall with a miniaturised electronically-controlled
drug delivery system (20×17.5×5 mm3) designed to be
skull-mounted in rats. The device features a micropump
connected to two 8-mm-long silicon microprobes with a
cross section of 250×250 μm2 and integrated fluid microchannels.
Using an external electronic control unit, the
device allows infusion of 16 metered doses (0.25 μL each,
8 per silicon shaft). Each dosage requires 3.375 Ws of
electrical power making the device additionally compatible
with state-of-the-art wireless headstages. A dosage precision of 0.25±0.01 μL was determined in vitro before in vivo tests were carried out in awake rats. No passive leakage from the loaded devices into the brain could be detected using methylene blue dye. Finally, the device was
used to investigate the effects of the NMDA-receptor
antagonist 3-((R)-2-Carboxypiperazin-4-yl)-propyl-1-
phosphonic acid, (R)-CPP, administered directly into
the prefrontal cortex of rats during performance on a
task to assess visual attention and impulsivity. In agreement with previous findings using conventional tethered
infusion systems, acute (R)-CPP administration produced
a marked increase in impulsivity. S. Zehnle, F. Schwemmer, G. Roth, F. von Stetten, R. Zengerle, N. PaustCentrifugo-dynamic inward pumping of liquids on a centrifugal microfluidic platform
2012 Lab Chip (Lab on a Chip) 2012 , volume : 12, pages : 5142 - 5145» show abstract « hide abstract Abstract We present a method to pump liquids in a centrifugal microfluidic spinning disk from a radial
outward position to a radial inward position. Centrifugal forces are applied to compress air in a
cavity, this way storing pneumatic energy. The cavity is connected to an outlet channel having a lower
hydraulic resistance compared to the inlet channel. The stored pneumatic energy is quickly released
by fast reduction of rotational frequency. This way liquid is transported mainly through the channel
with lower resistance, directing the liquid radially inwards. Pump efficiencies of .75% per pump cycle
have been demonstrated for water, ethanol, a highly viscous lysis buffer and whole blood. By
employing three pump cycles, water has been pumped radially inwards with an efficiency of .90%.
The inward pumping requires centrifugation only, which is intrinsically available on every centrifugal
microfluidic platform.
Download file A. Tropmann, L. Tanguy, P. Koltay, R. Zengerle, L. RieggerCompletely superhydrophobic PDMS surfaces for microfluidics 2012 Langmuir , volume : 28, issue : 22, pages : 8292 - 8295 G. Lammers, G. Roth, M. Heck, R. Zengerle, G. S. Tjabringa, E. M. Versteeg, T. Hafmans, R. Wismans, D. P. Reinhardt, E. T. P. Verwiel, P. L. J. M. Zeeuwen, J. Schalkwijk, R. Brock, W. F. Daamen, T. H. van KuppeveltConstruction of a Microstructured Collagen
Membrane Mimicking the Papillary Dermis
Architecture and Guiding Keratinocyte
Morphology and Gene Expression 2012 Macromol Biosci , volume : 12, pages : 675 - 691» show abstract « hide abstract Abstract A papillary-structured collagen fibril membrane is created, mimicking the 3D-architecture of
the human papillary dermis. Primary human keratinocytes cultured to confluency on papillarstructured
films are compared to keratinocytes cultured on flat membranes. Microscopical
evaluation reveals the presence of morphologically distinct
cells at the base of the papillar structures that are not
observed on flat membranes. Gene expression microarrays
and RT-qPCR indicate that these cells are in a more proliferative/
migrational state, whereas cells on flat membranes
have a more differentiated expression profile.
Immunohistochemical stainings confirm these results. In
conclusion, specific collagen architecture can direct keratinocyte
behavior, and this may be used to further improve
skin regeneration. Mitsakakis K, Sekula-Neuner S, Lenhert S, Fuchs H, Gizeli EConvergence of Dip-pen nanolithography and acoustic biosensors towards a rapid-analysis multi-sample microsystem 2012 Analyst , volume : 137, pages : 3076 - 3082 A. Kloke, C. Köhler, R. Gerwig, R. Zengerle, S. KerzenmacherCyclic Electrodeposition of PtCu Alloy: Facile Fabrication
of Highly Porous Platinum Electrodes 2012 Adv Mater , volume : 24, pages : 2916 - 2921 B. Faltin, S. Wadle, G. Roth, R. Zengerle, F. von StettenMediator Probe PCR: A Novel Approach for Detection of Real-Time PCR Based on Label-Free Primary Probes and Standardized Secondary Universal Fluorogenic Reporters
2012 Clin Chem , volume : 58, issue : 11, pages : 1546 - 1556 Daniel Mark, Felix von Stetten, Roland ZengerleMicrofluidic Apps for off-the-shelf instruments 2012 Lab Chip , volume : 12, pages : 2464 - 2468 B. Landenberger, H. Hoefemann, S. Wadle, A. RohrbachaMicrofluidic sorting of arbitrary cells with dynamic optical tweezers 2012 Lab Chip , volume : 12, pages : 3177 - 3183» show abstract « hide abstract Abstract Optical gradient forces generated by fast steerable optical tweezers are highly effective for sorting
small populations of cells in a lab-on-a-chip environment. The presented system can sort a broad
range of different biological specimens by an automated optimisation of the tweezer path and velocity
profile. The optimal grab positions for subsequent trap and cell displacements are estimated from the
intensity of the bright field image, which is derived theoretically and proven experimentally. We
exhibit rapid displacements of 2 µm small mitochondria, yeast cells, rod-shaped bacteria and 30 mm
large protoplasts. Reliable sorting of yeast cells in a microfluidic chamber by both morphological
criteria and by fluorescence emission is demonstrated. S.K. Vashist, A. G. Venkatesh, K. Mitsakakis, G. Czilwik, G. Roth, F. von Stetten, R. ZengerleNanotechnology-Based Biosensors and Diagnostics:
Technology Push versus Industrial/Healthcare Requirements 2012 BioNanoSci. , volume : 2, pages : 115 - 126» show abstract « hide abstract Abstract There have been considerable advances in the field
of nanotechnology-based biosensors and diagnostics (NBBD)
during the last two decades. These include the production of
nanomaterials (NMs), employing them for new biosensing
and diagnostic applications, their extensive characterization
for in vitro and in vivo applications, and toxicity analysis. All
these developments have led to tremendous technology push
and successful demonstrations of several promising NBBD.
However, there has been a significant lag in their commercialization,
especially due to the lack of international regulatory
guidelines for evaluating the safety of NMs and the growing
public concerns about their toxicity. Despite these
numerous advances and the recent regulatory approval
of several NMs, it still remains to be seen if NBBD are
superior to conventional ones (not based on NMs), reliable,
reproducible, cost effective, and robust enough to
meet the requirements of industries and healthcare. This
manuscript provides a critical review of NBBD, the technology
push, and the industrial/healthcare requirements. A. Ernst, K. Mutschler, L. Tanguy, N. Paust, R. Zengerle, P. KoltayNumerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets 2012 sensors , volume : 12, pages : 10550 - 10565» show abstract « hide abstract Abstract In this paper a multi-disciplinary simulation of a capacitive droplet sensor based
on an open plate capacitor as transducing element is presented. The numerical simulations
are based on the finite volume method (FVM), including calculations of an electric field
which changes according to the presence of a liquid droplet. The volume of fluid (VOF)
method is applied for the simulation of the ejection process of a liquid droplet out of a
dispenser nozzle. The simulations were realised using the computational fluid dynamic
(CFD) software CFD ACE+. The investigated capacitive sensing principle enables to
determine the volume of a micro droplet passing the sensor capacitor due to the induced
change in capacity. It could be found that single droplets in the considered volume range of
5 nL < Vdrop < 100 nL lead to a linear change of the capacity up to ΔQ < 30 fC. The
sensitivity of the focused capacitor geometry was evaluated to be Si = 0.3 fC/nL. The
simulation results are validated by experiments which exhibit good agreement. Dennis Trebbels, Felix Fellhauer, Michael Jugl, Gerd Haimerl, Mart Min, Roland ZengerleOnline Tissue Discrimination for Transcutaneous Needle Guidance Applications Using Broadband Impedance Spectroscopy 2012 Ieee T Bio-med Eng , volume : 59, issue : 2, pages : 494 - 503» show abstract « hide abstract Abstract This paper reports on a novel system architecture for
measuring impedance spectra of a biological tissue close to the tip
of a hollow needle. The measurement is performed online using fast
broadband chirp signals. The time domain measurement raw data
are transformed into the transfer function of the tissue in frequency
domain. Correlation technique is used to analyze the characteristic
shape of the derived tissue transfer function with respect to
known “library functions” for different types of tissue derived in
earlier experiments. Based on the resulting correlation coefficients
the exact type of tissue is determined. A bipolar coaxial needle is
constructed, simulated by finite element method and tested during
various in vitro and in vivo experiments. The results show a good
spatial resolution of approximately 1.0mm for a needle with a diameter
of 2.0 mm. The correlation coefficients for the three tested
tissue types muscle, fat, and blood allow for a clear tissue classification.
Best results have been obtained using the characteristic
phase diagrams for each tissue. Correlated to the corresponding library
transfer function the coefficients are in the range of+0.96 to
+0.99 for the matching tissue. In return, the resulting coefficients
for correlation with nonmatching tissues are in the range of −0.93
to +0.81. J. Hoffmann, L. Riegger, F. Bundgaard, D. Mark, R. Zengerle, J. DucréeOptical non-contact localization of liquid-gas interfaces on disk during rotation for measuring flow rates and viscosities 2012 Lab Chip (Lab on a Chip) 2012 , volume : 12, pages : 5231 - 5236» show abstract « hide abstract Abstract We present a novel technique for the spatio-temporally resolved localization of liquid-gas interfaces
on centrifugal microfluidic platforms based on total internal reflection (TIR) at the channel wall. The
simple setup consists of a line laser and a linear image sensor array mounted in a stationary
instrument. Apart from identifying the presence of usually unwanted gas bubbles, the here described
online meniscus detection allows to measure liquid volumes with a high precision of 1.9%.
Additionally, flow rates and viscosities (range: 1–12 mPa s, precision of 4.3%) can be sensed even
during rotation at frequencies up to 30 Hz.
Download file S.Herrlich, S.Spieth, S.Messner, R.ZengerleOsmotic micropumps for drug delivery 2012 Adv Drug Deliver Rev , volume : 64, pages : 1617 - 1627» show abstract « hide abstract Abstract This paper reviews miniaturized drug delivery systems applying osmotic principles for pumping. Osmotic
micropumps require no electrical energy and consequently enable drug delivery systems of smallest size
for a broad field of new applications. In contrast to common tablets, these pumps provide constant (zeroorder)
drug release rates. This facilitates systems for long term use not limited by gastrointestinal transit
time and first-pass metabolism. The review focuses on parenteral routes of administration targeting drug delivery
either in a site-specific or systemic way. Osmotic pumps consist of three building blocks: osmotic
agent, solvent, and drug. This is used to categorize pumps into (i) single compartment systems using water
from body fluids as solvent and the drug itself as the osmotic agent, (ii) two compartment systems employing
a separate osmotic agent, and (iii) multi-compartment architectures employing solvent, drug and osmotic
agent separately. In parallel to the micropumps, relevant applications and therapies are discussed. A. Tropmann, N. Lass, N. Paust, T. Metz, C. Ziegler, R. Zengerle, P. KoltayPneumatic Dispensing of Nano- to Picoliter Droplets of Liquid Metal with the StarJet Method for Rapid Prototyping of Metal Microstructures 2012 Microfluid Nanofluid , volume : 12, pages : 75 - 84» show abstract « hide abstract Abstract This work presents a new, simple and robust, pneumatically actuated method for the generation of liquid metal micro droplets in the nano- to picoliter range. The so called StarJet dispenser utilizes a star-shaped nozzle geometry that stabilizes liquid plugs in its center by means of capillary forces. Single droplets of liquid metal can be pneumatically generated by interaction of the sheathing gas flow in the outer grooves of the nozzle and the liquid metal. For experimental validation, a print head was build consisting of silicon chips with a star-shaped nozzle geometry and a heated actuator (up to 280 °C). The silicon chips are fabricated by Deep Reactive Ion Etching (DRIE). Chip designs with different star-shaped geometries were able to generate droplets with diameters in the range of the corresponding nozzle diameters. The StarJet can be operated in two modes: Either continuous droplet dispensing mode or drop on demand (DoD) mode. The continuous droplet generation mode for a nozzle with 188 µm diameter shows tear-off frequencies between 25 Hz and 120 Hz, while droplet diameters remain constant at 210 µm for each pressure level. Metal columns were printed with a thickness of 0.5 to 1.0 mm and 30 mm height (aspect ratio >30) to demonstrate the directional stability of droplet ejection and its potential as a suitable tool for direct prototyping of metal microstructures. Arne Kloke, Christian Köhler, Roland Zengerle, Sven KerzenmacherPorous Platinum Electrodes Fabricated by Cyclic Electrodeposition of PtCu Alloy: Application to Implantable Glucose Fuel Cells 2012 J Phys Chem C , volume : 116, pages : 19689 - 19698» show abstract « hide abstract Abstract We demonstrate the application of cyclic
electrodeposition of PtCu alloy to fabricate porous platinum
electrodes for implantable glucose fuel cells. Depending on the
number of deposition cycles, electrodes with controllable
specific surface area can be fabricated, their roughness factors
ranging from 20 (slightly roughened) to 3100 (highly porous).
Adjusting the specific surface area of the electrode from low to
high determines whether it functions as cathode or anode,
respectively. Compared to state of the art, this process is
beneficial due to shorter fabrication times, lower temperatures,
and the requirement of only one process for the fabrication of
both electrodes. Correspondingly fabricated glucose fuel cells showed a power density of 5.1 μW cm−2 under close to
physiological conditions, which is an improvement by 16% compared to earlier designs. During continuous operation over 90
days the fuel cell showed a mean continuous decay of about 0.8% per day, which is related to catalyst poisoning at the anode.
Future work will thus have to focus on the improvement of long-term stability instead of power density.
■ INTRODUCTION S. Rubenwolf, S. Sané, L. Hussein, J. Kestel, F. von Stetten, G. Urban, M. Krueger, R. Zengerle, S. KerzenmacherProlongation of electrode lifetime in biofuel cells by periodic enzyme renewal 2012 Appl Microbiol Biotechnol , volume : 96, pages : 841 - 849» show abstract « hide abstract Abstract Abstract Enzymatically catalyzed biofuel cells show unique
specificity and promise high power densities, but suffer from a limited lifetime due to enzyme deactivation. In the present work, we demonstrate a novel concept to extend the lifetime of a laccase-catalyzed oxygen reduction cathode in which we decouple the electrode lifetime from the limited enzyme lifetime by a regular resupply of fresh enzymes. Thereto, the adsorption behavior of laccase from Trametes versicolor to buckypaper electrode material, as well as its time-dependent deactivation characteristics, has been investigated. Laccase shows a Langmuir-type adsorption to the carbon nanotube-based buckypaper electrodes, with a mean residence time of 2 days per molecule. In a citrate buffer of pH 5, laccase does not show any deactivation at room temperature for 2 days and exhibits a half-life of 9 days. In a long-term experiment, the laccase
electrodes were operated at a constant galvanostatic load. The laccase-containing catholyte was periodically exchanged
against a freshly prepared one every second day to provide
sufficient active enzymes in the catholyte for the replacement of desorbed inactive enzymes. Compared to a corresponding control experiment without catholyte exchange, this procedure resulted in a 2.5 times longer cathode lifetime of 19±9 days in which the electrode showed a potential above 0.744 V vs. normal hydrogen electrode at 110 μAcm−2. This clearly indicates the successful exchange of molecules by desorption and re-adsorption and is a first step toward the realization of a selfregenerating enzymatic biofuel cell in which enzyme-producing microorganisms are integrated into the electrode to continuously resupply fresh enzymes. Jochen Rupp, Manuela Schmidt, Susanne Münch, Markus Cavalar, Ulf Steller, Jürgen Steigert, Michael Stumber, Christian Dorrer, Peter Rothacher, Roland Zengerle, Martina DaubRapid microarray processing using a disposable hybridization chamber with an integrated micropump 2012 Lab Chip , volume : 12, pages : 1384 - 1388» show abstract « hide abstract Abstract We present a disposable microarray hybridization chamber with an integrated micropump to speed up
diffusion based reaction kinetics by generating convective flow. The time-to-result for the hybridization
reaction was reduced from 60 min (standard protocol) down to 15 min for a commercially available
microarray. The integrated displacement micropump is pneumatically actuated. It includes two active
microvalves and is designed for low-cost, high volume manufacturing. The setup is made out of two
microstructured polymer parts realized in polycarbonate (PC) separated by a 25 mm thermoplastic
elastomer (TPE) membrane. Pump rate can be controlled between 0.3 µl/s and 5.7 µl/s at actuation
frequencies between 0.2 Hz and 8.0 Hz, respectively. Jochen Hoffmann, Martin Trotter, Felix von Stetten, Roland Zengerle, Günter RothSolid-phase PCR in a picowell array for immobilizing and arraying 100,000 PCR products to a microscope slide 2012 Lab Chip , volume : 12, issue : 17, pages : 3049 - 3054» show abstract « hide abstract Abstract We present a method for performing highly parallel PCR reactions in a picowell array (PWA) simultaneously immobilizing generated PCR products covalent and spatially-resolved onto a microscope slide via solid-phase PCR (SP-PCR). This so called PWA-SP-PCR is performed in picowell arrays featuring 100,000 wells∙cm^-2 of 19 pL reaction volumes with a surface-to-volume-ratio of 0.2 µm-1. Positive signals are obtained in 97.2 % of the 110,000 wells on an area of 110 mm^2. Immobilized DNA is either detected sequence-unspecific via streptavidin-Cy5 or sequence-specific by Cy3 labeled hybridization probes. Amplification and immobilization is demonstrated for template DNA ranging from 100 bp up to 1513 bp length. Compared to widely established emulsion based PCR (emPCR) approaches, leading to PCR products immobilized onto bead surfaces in highly parallel manner, the novel technique results in direct spatial registration of immobilized PCR products in a microarray format. This enables the subsequent use for massively parallel analysis similar to standard microarrays. H. Hoefemann, S. Wadle, N. Bakhtina, V. Kondrashov, N. Wangler, R. ZengerleSorting and lysis of single cells by BubbleJet technology 2012 Sensors and Actuators B , volume : 168, pages : 442 - 445 S Spieth, A Schumacher, C Kallenbach, S Messner, R ZengerleThe NeuroMedicator—a micropump integrated with silicon microprobes for drug delivery in neural research 2012 J Micromech Microeng , volume : 22, page : 065020 T. Hutzenlaub, S. Thiele, R. Zengerle, C. ZieglerThree-Dimensional Reconstruction of a LiCoO2 Li-Ion Battery Cathode 2012 Electrochem Solid St , volume : 15, issue : 3, pages : A33 - A36» show abstract « hide abstract Abstract In the reported work, we reconstruct a LiCoO2 cathode three-dimensionally, for the first time differentiating between all three constituents: (i) active material, (ii) binder and (iii) pore space for this specific material. We apply a hybrid method of manual and grey-scale threshold segmentation to reconstruct a cuboid with a volume of approximately 4500 µm3. The reconstructed geometry is characterised to support the data basis of homogenized cathode models. We solve numerically for electrical conductivity and derive electrical tortuosity analytically from the result. Pore space connectivity and pore size distribution are also calculated. The segmented images are provided as supplementary electronic material. A. Gulliksen, H. Keegan, C. Martin, J. O’Leary, L. A. Solli, I. M. Falang, P. Grønn, A. Karlg°ard, M. M. Mielnik, Ib-R.Johansen, Terje R. Tofteberg, T. Baier, R. Gransee, K. Drese, T. Hansen-Hagge, L. Riegger, P. Koltay, R. Zengerle, F. Karlsen, D. Ausen, , , Liv Furuberg2, 4Towards a “Sample-In, Answer-Out” Point-of-Care
Platform for Nucleic Acid Extraction and Amplification:
Using an HPV E6/E7mRNAModel System 2012 Journal of Oncology , volume : 2012, page : ID 905024» show abstract « hide abstract Abstract The paper presents the development of a “proof-of-principle” hands-free and self-contained diagnostic platform for detection
of human papillomavirus (HPV) E6/E7 mRNA in clinical specimens. The automated platform performs chip-based sample
preconcentration, nucleic acid extraction, amplification, and real-time fluorescent detection with minimal user interfacing. It
consists of two modular prototypes, one for sample preparation and one for amplification and detection; however, a common
interface is available to facilitate later integration into one single module. Nucleic acid extracts (n = 28) from cervical cytology
specimens extracted on the sample preparation chip were tested using the PreTect HPV-Proofer and achieved an overall detection
rate for HPV across all dilutions of 50%–85.7%. A subset of 6 clinical samples extracted on the sample preparation chip module
was chosen for complete validation on the NASBA chip module. For 4 of the samples, a 100% amplification for HPV 16 or 33 was
obtained at the 1 : 10 dilution for microfluidic channels that filled correctly. The modules of a “sample-in, answer-out” diagnostic
platform have been demonstrated from clinical sample input through sample preparation, amplification and final detection. Jochen Hoffmann, Sebastian Hin, Felix von Stetten, Roland Zengerle, Günter RothUniversal protocol for grafting PCR primers onto various lab-on-a-chip substrates for solid-phase PCR 2012 RSC Advances , volume : 2, issue : 9, pages : 3885 - 3889» show abstract « hide abstract Abstract A universal protocol for grafting PCR primers onto glass, PDMS, COP, COC, and PP is developed
and evaluated by solid-phase PCR (SP-PCR). Primers are immobilized in a PCR compatible way
featuring spots with high homogeneity and integrity. Furthermore, we show a protocol for binding a
PCR product to immobilized PCR primers via solid-phase PCR (SP-PCR). Previously reported
‘‘enhanced SP-PCR’’ (Z. Kahn et al. Anal. Biochem., 2008, 375, 391–393) is improved in terms of
factorial signal increase from 9.9 to 86.8 and specificity from 11.7 to 45.9. The presented
immobilization- and SP-PCR protocols may enable integration of DNA microarrays directly into
microfluidic lab-on-a-chip cartridges of various materials for analysis via SP-PCR. Beside planar
microarrays, another interesting application could be to coat the inner surfaces of a chip with PCR
primers to recover generated PCR products in digital PCR systems. back to the year overview A. Kloke, B. Biller, U. Kräling, S. Kerzenmacher, R. Zengerle, F. von StettenA Single Layer Glucose Fuel Cell Intended as Power Supplying Coating for Medical Implants 2011 Fuel Cells , volume : 11, issue : 2, pages : 316 - 326» show abstract « hide abstract Abstract We present a novel type of abiotically catalysed implantable
glucose fuel cell with anode and cathode placed side by side,using a Raney-platinum glucose oxidation anode with high tolerance towards oxygen. In contrast to conventional
assembly designs used for implantable glucose fuel cells, no
permeable cathode mounted in front of the anode to effect
oxygen depletion is required. At 2.2 ± 0.1 lW cm–2 the single layer fuel cell exhibits only half the maximum power
density of the conventional fuel cell, which solely stems
from the doubled total fuel cell area demand. Nevertheless,
the novel single layer design is advantageous in terms of
simplified fabrication and reduced overall thickness, facilitating implementation of the fuel cell as a power supplying coating directly on the surface of medical implants. Furthermore,the single layer design offers an attractive possibility to diminish the reduction of power density by limited oxygen mass transfer to the cathode by increasing the cathode to anode area proportion. With doubled cathode area proportion a by 36% higher power density can be reached. To calculate the optimum cathode to anode area proportions,we introduced an analytical model based on the experimentally determined polarisation resistances of the individual electrodes.
Keywords: Biomedical Devices, Energy Harvesting, Implantable
Glucose Fuel Cell, Oxygen Tolerant Platinum Electrodes,
Power Supply S Spieth, O Brett, K Seidl, A A A Aarts, M A Erismis, S Herwik, F Trenkle, S Tätzner, J Auber, M Daub, H P Neves, R Puers, O Paul, P Ruther, R ZengerleA floating 3D silicon microprobe array for neural drug delivery compatible with electrical recording 2011 J Micromech Microeng , volume : 21, pages : 125001 - (16pp)» show abstract « hide abstract Abstract This paper reports on the design, fabrication, assembly, and characterization of a three-dimensional (3D) silicon-based floating microprobe array for localized drug delivery to be applied in neuroscience research. The microprobe array is composed of a silicon platform into which up to four silicon probe combs with needle-like probe shafts can be inserted. Two dedicated positions in the array allow the integration of combs for drug delivery. The implemented comb variants feature 8-mm-long probe shafts with two individually addressable microchannels incorporated in one single shaft or distributed to two shafts. Liquid supply to the array is realized by a highly flexible 250-µm-thick multi-lumen microfluidic cable made from polydimethylsiloxane (PDMS). The specific design concept of the slim-base platform enables floating implantation of the array in the small space between brain and skull. In turn, the flexible cable mechanically decouples the array from any microfluidic interface rigidly fixed to the skull. After assembly of the array, full functionality is demonstrated and characterized at infusion rates from 1 to 5 µL/min. Further, the effect of a parylene-C coating on the water vapour and osmotic liquid water transport through the PDMS cable walls is experimentally evaluated by determining the respective transmission rates including the water vapour permeability of the used PDMS type. L. Hussein, S. Rubenwolf, F. von Stetten, G. Urban, R. Zengerle, M. Krueger, S. KerzenmacherA highly efficient buckypaper-based electrode material for mediatorless laccase-catalyzed dioxygen reduction 2011 Biosens Bioelectron , volume : 26, pages : 4133 - 4138» show abstract « hide abstract Abstract The redox enzyme laccase from Trametes versicolor efficiently catalyzes the oxygen reduction reaction
(ORR) in mediatorless biofuel cell cathodes when adsorbed onto multi-walled carbon nanotubes
(MWCNTs). In this work we demonstrate that the fabrication of MWCNTs in form of buckypaper (BP)
results in an excellent electrode material for laccase-catalyzed cathodes.
BPs are mechanically stable, self-entangling mats with high dispersion of MWCNTs resulting in easy to
handle homogeneous layers with highly mesoporous structures and excellent electrical conductivities.
All biocathodes have been electrochemically investigated in oxygen-saturated buffer at pH 5 by
galvanostatic polarization and potentiodynamic linear sweep voltammetry. Both methods confirm an
efficient direct interaction of laccase with BP with a high open circuit potential of 0.882V vs. normal
hydrogen electrode (NHE). The high oxygen reduction performance leads to high current densities of
422±71 µAcm−2 at a typical cathode potential of 0.744V vs. NHE.
When the current density is normalized to the mass of the electrode material (mass activity), the BPbased
film electrodes exhibit a 68-fold higher current density at 0.744Vvs.NHEthan electrodes fabricated
from the same MWCNTs in a non-dispersed agglomerated form as packed electrodes. This clearly shows
that MWCNTs can act more efficiently as cathode when prepared in form of BP. This can be attributed to
reduced diffusional mass transfer limitations and enhanced electrical conductivity.
BP is thus a very promising material for the construction of mediatorless laccase cathodes for ORR in
biofuel cells. In addition we demonstrated that these electrodes exhibit a high tolerance towards glucose,
the most common bioanode fuel. S. Kerzenmacher, U. Kräling, T. Metz, R. Zengerle, F. von StettenA potentially implantable glucose fuel cell with Raney-platinum film electrodes for improved hydrolytic and oxidative stability 2011 J Power Sources , volume : 196, pages : 1264 - 1272» show abstract « hide abstract Abstract We present an improved abiotically catalyzed glucose fuel cell, intended as energy harvesting tissue
implantable power supply for medical implants. The fuel cell is constructed from a Raney-platinum
film cathode deposited on a silicon substrate with micro-machined feedholes for glucose permeability,
arranged in front of a Raney-platinum film anode. A novelty is the application of platinum for
both electrodes and the complete abdication of hydrogel binders. This overcomes the limited stability
against hydrolytic and oxidative attack encountered with previous glucose fuel cells fabricated from
activated carbon particles dispersed in a hydrogel matrix. During performance characterization in phosphate
buffered saline under physiological concentrations of glucose and oxygen the diffusion resistance
to be expected from tissue capsule formation was taken into account. Despite the resulting limited oxygen
supply, the Raney-platinum fuel cells exhibit a power density of up to (4.4±0.2)µWcm−2 at 7.0%
oxygen saturation. This exceeds the performance of our previous carbon-based prototypes, and can be
attributed to the higher catalytic activity of platinum cathodes and in particular the increased oxygen
tolerance of the Raney-platinum film anodes. Michael Vosseler, Michael Jugl, Roland ZengerleA smart interface for reliable intradermal injection and infusion of high and low viscosity solutions 2011 Pharm Res-dordr , volume : 28, pages : 647 - 661» show abstract « hide abstract Abstract Purpose: We present a smart intradermal interface suitable for skin attached drug delivery devices. Our solution enables injections or infusions that are less invasive compared to subcutaneous injections and is leakage-free at the location of penetration.
Methods: The intradermal interface is based on a 31 gauge cannula embedded in a slider, movable relative to a carrier plate that can easily be fixed onto the skin. By simply pushing the slider the cannula is inserted into the dermis.
Results: We performed injections and infusions with stained water and polyethylene glycol (PEG) solution in ex vivo pig skin. The sizes of coloured spots in the skin range from 3.5 mm² to 15.4 mm² for stained water depending on the infused volume. Infusing stained PEG solution resulted in stained tissue areas about one order of magnitude larger. One of three investigated leakage modes is unacceptable but can be reliably avoided by proper site selection. At low flow rates and at the beginning of an infusion an initial back pressure overshoot was identified. This effect was identified as the limiting parameter for the design of small programmable or intelligent devices based on micro actuators.
Conclusions: With the proposed easy-to-use interface, intradermal injections and infusions can be performed reliably. Therefore, it is supposed to be an ideal and clinically relevant solution for self-administration of parenteral drugs in home care applications. Daniel Mark, Patrick Weber, Sascha Lutz, Maximilian Focke, Roland Zengerle, Felix von StettenAliquoting on the centrifugal microfluidic platform based on centrifugo-pneumatic valves 2011 Microfluid Nanofluid , volume : 10, pages : 1279 - 1288» show abstract « hide abstract Abstract We present a new method for aliquoting liquids
on the centrifugal microfluidic platform. Aliquoting is an
essential unit operation to perform multiple parallel assays
(‘‘geometric multiplexing’’) from one individual sample,
such as genotyping by real-time polymerase chain reactions
(PCR), or homogeneous immunoassay panels. Our method
is a two-stage process with an initial metering phase and a
subsequent transport phase initiated by switching a centrifugo-
pneumatic valve. The method enables aliquoting
liquids into completely separated reaction cavities. It includes
precise metering that is independent on the volume of prestored
reagents in the receiving cavities. It further excludes
any cross-contamination between the receiving cavities. We
characterized the performance for prototypes fabricated by
three different technologies: micro-milling, thermoforming
of foils, and injection molding. An initial volume of*90 ll
was split into 8 aliquots of 10 ll volume each plus a waste
reservoir on a thermoformed foil disk resulting in a coefficient
of variation (CV) of the metered volumes of 3.6%. A
similar volume of*105 ll was split into 16 aliquots of 6 ll
volume each on micro-milled and injection-molded disks
and the corresponding CVs were 2.8 and 2.2%, respectively.
Thus, the compatibility of the novel aliquoting structure to
the aforementioned prototyping and production technologies
is demonstrated. Additionally, the important question
of achievable volume precision of the aliquoting structure
with respect to the production tolerances inherent to each of
these production technologies is addressed experimentally
and theoretically. The new method is amenable to low cost
mass production, since it does not require any post-replication
surface modifications like hydrophobic patches. O Frey, P D van derWal, S Spieth, O Brett, K Seidl, O Paul, P Ruther, R Zengerle, N F de RooijBiosensor microprobes with integrated microfluidic channels for bi-directional neurochemical interaction 2011 J Neural Eng , volume : 8, page : 066001» show abstract « hide abstract Abstract This paper reports on silicon-based microprobes, 8 mm long and 250 μm × 250 μm
cross-section, comprising four recessed biosensor microelectrodes (50 μm × 150 μm) per
probe shank coated with an enzymatic layer for the selective detection of choline at multiple
sites in brain tissue. Integrated in the same probe shank are up to two microfluidic channels for
controlled local liquid delivery at a defined distance from the biosensor microelectrodes.
State-of-the-art silicon micromachining processing was applied for reproducible fabrication of
these experiment-tailored multi-functional probe arrays. Reliable electric and fluidic
interconnections to the microprobes are guaranteed by a custom-made holder. The reversible
packaging method implemented in this holder significantly reduces cost and assembly time
and simplifies storage of the biosensor probes between consecutive experiments. The
functionalization of the electrodes is carried out using electrochemically aided adsorption.
This spatially controlled deposition technique enables a parallel deposition of membranes and
is especially useful when working with microelectrode arrays. The achieved biosensors show
adequate characteristics to detect choline in physiologically relevant concentrations at
sufficient temporal and spatial resolution for brain research. Sensitivity to choline better than
10 pA μM−1, detection limit below 1 μM and response time of 2 s were obtained. The
proposed combination of biosensors and microfluidic injectors on the same microprobe allows
simultaneous chemical stimulation and recording as demonstrated in an agarose gel-based
brain phantom. Marc Karle, Johannes Wöhrle, Junichi Miwa, Nils Paust, Günter Roth, Roland Zengerle, Felix von StettenControlled counter-flow motion of magnetic bead chains rolling along microchannels 2011 Microfluid Nanofluid , volume : 10, issue : 4, pages : 935 - 939» show abstract « hide abstract Abstract We demonstrate controlled transport of superparamagnetic
beads in the opposite direction of a laminar
flow. A permanent magnet assembles 200 nm magnetic
particles into about 200 lm long bead chains that are
aligned in parallel to the magnetic field lines. Due to a
magnetic field gradient, the bead chains are attracted
towards the wall of a microfluidic channel. A rotation of
the permanent magnet results in a rotation of the bead
chains in the opposite direction to the magnet. Due to
friction on the surface, the bead chains roll along the
channel wall, even in counter-flow direction, up to at a
maximum counter-flow velocity of 8 mm s(-1). Based on
this approach, magnetic beads can be accurately manoeuvred
within microfluidic channels. This counter-flow
motion can be efficiently be used in Lab-on-a-Chip systems,
e.g. for implementing washing steps in DNA
purification. Mitsakakis K, Gizeli EDetection of multiple cardiac markers with an integrated acoustic platform for cardiovascular risk assessment 2011 Anal Chim Acta , volume : 699, pages : 1 - 5 Christoph Ziegler, Simon Thiele, Roland ZengerleDirect three-dimensional reconstruction of a nanoporous catalyst layer for a polymer electrolyte fuel cell 2011 J Power Sources , volume : 196, issue : 4, pages : 2094 - 2097» show abstract « hide abstract Abstract The direct three-dimensional reconstruction of a polymer electrolyte fuel cell cathode catalyst layer from focused ion beam/scanning electron microscope (FIB/SEM) images is presented. The carbon and pore distribution is shown and quantitatively analysed. A new catalyst layer sample (Fumapem-F950/HiSpec13100) is sliced with FIB and a series of SEM images is taken. The images are registered, segmented and a three-dimensional stack is reconstructed. The three-dimensional carbon and pore distribution is shown. Based on the reconstruction the pore size distribution is evaluated. The total porosity and the unconnected pores space is analysed. The fully segmented 2D images are provided as supplemental material to this paper for future analysis and modeling work.
Keywords
Polymer electrolyte fuel cell;
Porous catalyst layer;
Three-dimensional reconstruction N Wangler, L Gutzweiler, K Kalkandjiev, C Müller, F Mayenfels, H Reinecke, R Zengerle, N PaustHigh-resolution permanent photoresist laminate TMMF for sealed microfluidic structures in biological applications 2011 J Micromech Microeng , volume : 21, page : 095009» show abstract « hide abstract Abstract We demonstrate the use of photosensitive epoxy laminate TMMF S2045 for the fabrication
and sealing of tapered microfluidic channels. The 45 μm thick resist enables the fabrication of
shallow sealed cavities featuring extreme aspect ratios of less than 1:40 (h = 45 μm, w =
2000 μm). It also provides high resolution and enables minimum feature sizes of 10 μm. For
the fabrication of free-standing structures, an aspect ratio of up to 7:1 was achieved. The
dry-film photoresist can be applied easily by lamination onto structured substrates. The total
thickness variation of the resist across a 100 mm wafer was determined to be less than
±0.6 μm. Process parameters for the fabrication and sealing of various micro-channels are
discussed and optimized in this paper. The main focus was to minimize thermal impact during
lamination, soft-bake, exposure and post–exposure bake, which could lead to lid sagging or
channel clogging due to liquefaction of uncured resist. We tested TMMF according to ISO
10995-5 and found it to be non-cytotoxic, enabling its use for biological applications.
Swelling of less than 5% for incubation of the dry-film resist in several biologically relevant
solvents, buffers and cleaning solutions was observed. Azmi Yusof, Helen Keegan, Cathy D. Spillane, Orla M. Sheils, Cara M. Martin, John J. O’Leary, Roland Zengerle, Peter KoltayInkjet-like printing of single-cells 2011 Lab Chip , volume : 11, pages : 2447 - 2454» show abstract « hide abstract Abstract Cell sorting and separation techniques are essential tools for cell biology research and for many
diagnostic and therapeutic applications. For many of these applications, it is imperative that
heterogeneous populations of cells are segregated according to their cell type and that individual cells
can be isolated and analysed. We present a novel technique to isolate single cells encapsulated in
a picolitre sized droplet that are then deposited by inkjet-like printing at defined locations for
downstream genomic analysis. The single-cell-manipulator (SCM) developed for this purpose consists
of a dispenser chip to print cells contained in a free flying droplet, a computer vision system to detect
single-cells inside the dispenser chip prior to printing, and appropriate automation equipment to print
single-cells onto defined locations on a substrate. This technique is spatially dynamic, enabling cell
printing on a wide range of commonly used substrates such as microscope slides, membranes and
microtiter plates. Demonstration experiments performed using the SCM resulted in a printing
efficiency of 87% for polystyrene microbeads of 10 mm size. When the SCM was applied to a cervical
cancer cell line (HeLa), a printing efficiency of 87% was observed and a post-SCM cell viability rate of
75% was achieved. M. Pospischil, K. Zengerle, J. Specht, G. Birkle, P. Koltay, R. Zengerle, A. Henning, M. Neidert, C. Mohr, F. Clement, D. BiroInvestigations on Thick-Film-Paste Rheology for Dispensing Applications 2011 Energy Procedia , volume : 8, pages : 449 - 454» show abstract « hide abstract Abstract In order to establish dispensing as a promising metallization process in silicon photovoltaics, equipment and metal
pastes require further optimization. By conducting several rheological experiments based on rotational tests, shear
thinning as well as thixotropic behavior of thick-film pastes were investigated. Both are crucial parameters for
continuous dispensing of 60 μm fingers with high aspect ratios. Flow rate fluctuations during dispensing though
imply stress peaks that may disturb a continuous paste flow. Thus, a comparison of the flow rate of two pastes was
conducted. A comparison of dispensed cells with screen-printed reference cells, on multi-crystalline wafer-material,
showed an efficiency increase of 0.3%abs. on average. This is mainly caused by reduced finger widths and higher
aspect ratios of dispensed fingers. K Kalkandjiev, L Riegger, D Kosse, M Welsche, L Gutzweiler, R Zengerle, P KoltayMicrofluidics in silicon/polymer technology as a cost-efficient alternative to silicon/glas 2011 J Micromech Microeng , volume : 21, page : 025008 (8p» show abstract « hide abstract Abstract We investigate TMMF photopolymer as a cost efficient alternative to glass for the liquid tight sealing of high density silicon microchannels. TMMF enables low temperature sealing and access to structures underneath via lamination and standard UV lithography instead of costly glass machining and anodic bonding. TMMF is highly transparent and has a low autofluorescence for wavelengths larger than 400 nm. As the photopolymer is too thin for implementing bulky World-to-Chip-interfaces, we propose adhesive bonding of COC modules. All materials were tested according ISO 10993-5 and showed no cytotoxic effects on the proliferation of L929 cells. To quantify the cost efficiency of the proposed techniques, we used an established Si/Pyrex nanoliter dispenser as a reference and replaced structured Pyrex wafers by TMMF laminates and COC modules. Thus, consumable costs and time effort were reduced by 90 % respectively 35 % for the sealing and 80 % respectively 75 % for implementing the World-to-Chip interface. Liquid tightness was proved by applying a pressure of 0,2 MPa for 5 h without delamination or cross talk between neighbouring microchannels separated from each other by 100 µm. In contrast to anodic bonding, the proposed techniques are tolerant to surface inhomogenities. They enable manufacturing of silicon/polymer microfluidics at significantly lower costs and without compromising the performance compared to corresponding silicon/glass devices. M. Focke, D. Kosse, D. Al-Bamerni, S. Lutz, C. Mueller, H. Reinecke, R. Zengerle, F. von StettenMicrothermoforming of microfluidic substrates by soft lithography (µTSL): optimization using design of experiments 2011 J Micromech Microeng , volume : 21, issue : 11, pages : 115001 - 115012» show abstract « hide abstract Abstract We present a detailed analysis of microthermoforming by soft lithography (µTSL) for replication of foil-based microfluidic substrates. The process was systematically optimized by design of experiments (DOE) enabling fabrication of defect-free lab-on-a-chip devices. After the assessment of typical error patterns we optimized the process toward the minimum deviation between mold and thermoformed foil substrates. The following process parameters have most significant impact on the dimensional responses (p < 0.05): critical temperature before start of evacuation, molding temperature, pressure of pre-stretching and duration of pre-stretching as well as duration of molding pressure. The most relevant parameter is molding temperature with >40% relative impact. The DOE results in an empirical process model with a maximum deviation between the prediction and experimental proof of 2% for the optimum parameter set. Finally, process optimization is validated by the fabrication and testing of a microfluidic structure for blood plasma separation from human whole blood. The optimized process enabled metering of a nominal volume of 4.0 mu l of blood plasma with an accuracy deviation of 3% and a metering precision of +/- 7.0%. The µTSL process takes about 30 min and easily enables the replication of 300 mu m wide microchannels having vertical sidewalls without any draft angles in a well-controllable way. It proves to be suitable for multiple applications in the field of microfluidic devices. Mitsakakis K, Gizeli EMulti-sample acoustic biosensing microsystem for protein interaction analysis 2011 Biosens Bioelectron , volume : 26, pages : 4579 - 4584 Simon Thiele, Roland Zengerle, Christoph ZieglerNano-Morphology of a Polymer Electrolyte Fuel Cell Catalyst Layer—Imaging, Reconstruction and Analysis 2011 Nano Res , volume : 4, issue : 9, pages : 849 - 860» show abstract « hide abstract Abstract The oxygen reduction reaction (ORR) in the cathode catalyst layer (CCL) of polymer electrolyte fuel cells (PEFC)
is one of the major causes of performance loss during operation. In addition, the CCL is the most expensive
component due to the use of a Pt catalyst. Apart from the ORR itself, the species transport to and from the
reactive sites determines the performance of the PEFC. The effective transport properties of the species in the
CCL depend on its nanostructure. Therefore a three-dimensional reconstruction of the CCL is required. A series
of two-dimensional images was obtained from focused ion beam - scanning electron microscope (FIB-SEM)
imaging and a segmentation method for the two-dimensional images has been developed. The pore size
distribution (PSD) was calculated for the three-dimensional geometry. The influence of the alignment and the
anisotropic pixel size on the PSD has been investigated. Pores were found in the range between 5 nm and 205 nm.
Evaluation of the Knudsen number showed that gas transport in the CCL is governed by the transition flow
regime. The liquid water transport can be described within continuum hydrodynamics by including suitable
slip flow boundary conditions. Ernst, Andreas, Ju, Lin, Vondenbusch, Bernhard, Zengerle, Roland, Koltay, PeterNoncontact Determination of Velocity and Volume of Nanoliter Droplets on the Fly 2011 Ieee Sens J , volume : 11, issue : 8, pages : 1736 - 1742» show abstract « hide abstract Abstract We present a sensor for measuring volume and velocity
of dispensed nanoliter droplets in a noncontact manner on
the fly. The sensor-setup has a total thickness of 3.2 mm and can
easily be mounted underneath any given nanoliter dispenser for
continuous online monitoring of its dispensing performance. The
principle is based on the interaction of dispensed single droplets
of sample liquid passing the electric field of an open plate capacitor.
The effect depends on droplet parameters like volume, velocity,
and dielectric constant and is discussed in the paper. The
presented data analysis enables a velocity independent volume determination
of water droplets in the range from 26 to 82 nl with
an accuracy of 3 nl. The sensor signal is sensitive to the alignment
of the flight path of the nanoliter droplets within the 1.2-mm wide
open capacitor and can lead to systematic volume errors of up to
Delta V approx. 12 nl. The impact of different dielectric constants can only
be differentiated for very high variations; thus, the sensor needs to
be calibrated to the different types of liquids. F. Trenkle, S. Haeberle, R. ZengerleNormally-closed peristaltic micropump with re-usable actuator and disposable fluidic chip 2011 Sensor Actuat B-chem , volume : 154, issue : 2, pages : 137 - 141» show abstract « hide abstract Abstract We present a new peristaltic micropump offering three key features: (i) a disposable pump body and a reuseable
actuator unit, (ii) an intrinsic normally-closed mechanism blocking unintended liquid flows up to
a pressure of 100 kPa and (iii) a backpressure independent pump performance up to 40 kPa. The modular
concept basing on a re-usable actuator unit and a low-cost disposable microfluidic chip enables an easy
and cost-efficient exchange of all contaminated parts after use, which addresses especially the needs in
the health care sector. The intrinsic normally-closed feature blocks liquid flow in both directions up to a
pressure difference of 100 kPa when the electric power is off. The micropump is actuated in a peristaltic
manner by three piezostack actuators. Up to a frequency of 15 Hz the pump rate increases linearly with
operation frequency leading to a pump rate of 120 µL/min. This was proved for an operation voltage of
140V by pumping water. In addition the pump rate is independent on backpressure up to 40 kPa and
shows a linear decrease for higher pressure differences. The maximum achievable backpressure at zero
flow rate was extrapolated to be 180 kPa. As for all peristaltic micropumps, the pump is bidirectional, e.g.
the pump direction can be changed forward to reverse mode. Stefanie Rubenwolf, Sven Kerzenmacher, Roland Zengerle, Felix von StettenStrategies to extend the lifetime of bioelectrochemical enzyme electrodes for biosensing and biofuel cell applications 2011 Appl Microbiol Biot , volume : 89, issue : 5, pages : 1315 - 1322» show abstract « hide abstract Abstract Enzymes are powerful catalysts for biosensor
and biofuel cell electrodes due to their unique substrate
specificity. This specificity is defined by the amino acid
chain's complex three-dimensional structure based on noncovalent
forces, being also responsible for the very limited
enzyme lifetime of days to weeks. Many electrochemical
applications, however, would benefit from lifetimes over
months to years. This mini-review provides a critical
overview of strategies and ideas dealing with the problem
of short enzyme lifetime, which limits the overall lifetime
of bioelectrochemical electrodes. The most common
approaches aim to stabilize the enzyme itself. Various
immobilization techniques have been used to reduce
flexibility of the amino acid chain by introducing covalent
or non-covalent binding forces to external molecules. The
enzyme can also be stabilized using genetic engineering
methods to increase the binding forces within the protein or
by optimizing the environment in order to reduce destabilizing
interactions. In contrast, renewing the inactivated
catalyst decouples overall system lifetime from the limited
enzyme lifetime and thereby promises theoretically unlimited
electrode lifetimes. Active catalyst can be supplied by
exchanging the electrolyte repeatedly. Alternatively, integrated
microorganisms can display the enzymes on their
surface or secrete them to the electrolyte, allowing
unattended power supply for long-term applications.
Keywords Enzyme inactivation . Biofuel cell . Biosensor .
Amino acid replacement . Immobilization . Self-regeneration G. Grossmann, Woei-Jiun Guo, D. W. Ehrhardt, W. B. Frommer, R. V. Sit, S. R. Quake, M. MeierThe RootChip: An Integrated Microfluidic Chip for
Plant Science 2011 The Plant Cell , volume : 23, pages : 4234 - 4240» show abstract « hide abstract Abstract Studying development and physiology of growing roots is challenging due to limitations regarding cellular and subcellular
analysis under controlled environmental conditions. We describe a microfluidic chip platform, called RootChip, that
integrates live-cell imaging of growth and metabolism of Arabidopsis thaliana roots with rapid modulation of environmental
conditions. The RootChip has separate chambers for individual regulation of the microenvironment of multiple roots from
multiple seedlings in parallel. We demonstrate the utility of The RootChip by monitoring time-resolved growth and cytosolic
sugar levels at subcellular resolution in plants by a genetically encoded fluorescence sensor for glucose and galactose. The
RootChip can be modified for use with roots from other plant species by adapting the chamber geometry and facilitates the
systematic analysis of root growth and metabolism from multiple seedlings, paving the way for large-scale phenotyping of
root metabolism and signaling. T. Hutzenlaub, N. Paust, R. Zengerle, C. ZieglerThe effect of wetting properties on bubble dynamics and fuel distribution in the flow field of direct methanol fuel cells 2011 J Power Sources , volume : 196, pages : 8048 - 8056» show abstract « hide abstract Abstract We investigate CO2 bubble dynamics on the anode side of a direct methanol fuel cell (DMFC). In contrast
to previous studies, we analyse the effect of both channel wall and diffusion layer wettability by
observing two-phase flow from the side at different mean velocities of the fuel supply. Hydrophobic and
hydrophilic flow channel surfaces are compared experimentally. The hydrophilic flow channel leads to a
minimum pressure drop along the channel. Bubbles show virtually no pinning and consequently travel at
approximately the mean fuel velocity inside the channel. In contrast to this, we observe bubble pinning
in the hydrophobic flow channels. The critical fuel velocities necessary for detachment of the bubbles
mainly depends on bubble length. We identify and describe a new bubble bypass configuration where
fuel bypass channels are solely generated in a favourable position underneath a blocking bubble along
the diffusion layer. This enforces fuel to bypass the CO2 bubble at a large relative velocity close to the
diffusion layer, thus enhancing mass transfer. Our experimental findings are in excellent agreement with
a CFD/analytical model. This model allows for quantitative prediction of average bypass flow velocity. back to the year overview A. Kloke, S. Rubenwolf, C. Bücking, J. Gescher, S. Kerzenmacher, R. Zengerle, F. von StettenA versatile miniature bioreactor and its application to bioelectrochemistry studies 2010 Biosens Bioelectron , volume : 25, pages : 2559 - 2565» show abstract « hide abstract Abstract Often, reproducible investigations on bio-microsystems essentially require a flexible but well-defined
experimental setup, which in its features corresponds to a bioreactor. We therefore developed a miniature
bioreactor with a volume in the range of a few millilitre that is assembled by alternate stacking of
individual polycarbonate elements and silicone gaskets. All the necessary supply pipes are incorporated
as bore holes or cavities within the individual elements. Their combination allows for a bioreactor assembly
that is easily adaptable in size and functionality to experimental demands. It allows for controlling
oxygen transfer as well as the monitoring of dissolved oxygen concentration and pH-value. The system
provides access for media exchange or sterile sampling. A mass transfer coefficient for oxygen (kLa) of
4.3×10−3 s−1 at aflowrate of only 15 ml min−1 and a mixing time of 1.5 s at aflowrate of 11 ml min−1 were
observed for the modular bioreactor. Single reactor chambers can be interconnected via ion-conductive
membranes to form a two-chamber test setup for investigations on electrochemical systems such as fuel
cells or sensors. The versatile applicability of this modular and flexible bioreactor was demonstrated by
recording a growth curve of Escherichia coli (including monitoring of pH and oxygen) saturation, and
also as by two bioelectrochemical experiments. In the first electrochemical experiment the use of the
bioreactor enabled a direct comparison of electrode materials for a laccase-catalyzed oxygen reduction
electrode. In a second experiment, the bioreactor was utilized to characterize the influence of outer
membrane cytochromes on the performance of Shewanella oneidensis in a microbial fuel cell. Lutz Riegger, Oliver Strohmeier, Bernd Faltin, Roland Zengerle, Peter KoltayAdhesive bonding of microfluidic chips: influence of process parameters 2010 J Micromech Microeng , volume : 20, pages : 087003 - (5pp)» show abstract « hide abstract Abstract In this note, the influence of process parameters for adhesive bonding as a versatile approach
for the sealing of polymer microfluidic chips is investigated. Specifically, a process chain
comprising pre-processing, adhesive transfer as well as post-processing is presented and
parameter recommendations are provided. As a device for adhesive transfer, a modified
laminator is utilized which transfers thin layers of adhesive onto the chip surface, only via a
silicone roll. Using this device and a high temperature (Tg > 100 ◦C) epoxy adhesive,
adhesive layers in the range of 2–4 μm can be reproducibly transferred (CV < 4%). For best
bonding results, it is recommended to provide 2.5 μm thin layers of adhesive in combination
with a subsequent evacuation step at 10 mbar for 3 h. Further, it is proposed to integrate
capture channels near large, featureless areas to compensate for variations in processing and
thus prevent clogging of channels. K. Bürk, M. Wick, G. Roth, P. Decker, R. VoltzAntineuronal antibodies in sporadic late-onset cerebellar ataxia 2010 J Neurol , volume : 257, pages : 59 - 62» show abstract « hide abstract Abstract Sporadic late-onset cerebellar ataxia of
unknown cause is considered a neurodegenerative disorder
whose underlying mechanisms are still unknown. To
identify antineuronal autoantibodies, immunohistochemical
and immunoblotting techniques were performed in 67
patients with sporadic cerebellar degeneration of unknown
cause. Elevated P/Q-type voltage-gated calcium channel
(VGCC)-specific antibodies were found in eight patients
(11.9%). There was no hint of a paraneoplastic disorder in
any of the patients. The present findings suggest an
autoimmune contribution to the pathophysiology of a
subgroup of sporadic late-onset cerebellar ataxia. Tobias Metz, Nils Paust, Roland Zengerle, Peter KoltayCapillary driven movement of gas bubbles in tapered structures
2010 Microfluid Nanofluid , volume : 9, pages : 341 - 355» show abstract « hide abstract Abstract This article presents a study on the capillary
driven movement of gas bubbles confined in tapered
channel configurations. These configurations can be used to
transport growing gas bubbles in micro fluidic systems in a
passive way, i.e. without external actuation. A typical
application is the passive degassing of CO2 in micro direct
methanol fuel cells (lDMFC). Here, a one-dimensional
model for the bubble movement in wide tapered channels is
derived and calibrated by experimental observations. The
movement of gas bubbles is modelled on straight trajectories
based on a balance of forces. The bubble geometry is
considered as three dimensional. In the development of the
model, the effects of surface tension, inertia, viscosity,
dynamic contact angle and thin film deposition are considered.
It is found that in addition to viscous dissipation,
the dynamics related to the contact line—dynamic contact
angle and thin film deposition—are essential to describe
the gas bubble’s movement. Nevertheless, it was also found
that both of these effects, as modelled within this work,
have similar impact and are hard to distinguish. The model
was calibrated against experiments in a parameter range
relevant for the application of travelling gas bubbles in
passive degassing structures for lDMFCs. Stefanie Rubenwolf, Oliver Strohmeier, Arne Kloke, Sven Kerzenmacher, Roland Zengerle, Felix von StettenCarbon electrodes for direct electron transfer type laccase cathodes investigated by current density–cathode potential behaviour 2010 Biosens Bioelectron , volume : 26, pages : 841 - 845» show abstract « hide abstract Abstract Direct electron transfer from carbon electrodes to adsorbed laccase (EC 1.10.3.2) from Trametes versicolor
is widely used to enable mediatorless enzymatic biofuel cell cathodes. However, data published so far are
poorly comparable in terms of oxygen reduction performance. We thus present a comparative characterization
of carbon-based electrode materials as cathode in half-cell configuration, employing adsorbed
laccase as oxygen reduction catalyst.
Open circuit potentials and performances were significantly increased by laccase adsorption, indicating
the occurrence of direct electron transfer. At a potential of 0.5V vs. SCE volume-normalized current
densities of approximately 10, 37, 40, 70, and 77 µAcm−3 were measured for cathodes nanotubes, carbon
nanofibers and multi-walled carbon nanotubes, respectively.
In addition, we could show that both, carbon nanotubes and porous carbon tubes exhibit dramatically
lower current densities compared to graphite felt and carbon nanofibers when normalized to BET
surface instead of electrode volume. Further work will be required to clarify whether this stems from
material-dependent interaction of enzyme and electrode surface or constricted enzyme adsorption due
to agglomeration of the nanotubes. In case of the latter, an improved dispersion of the nanotubes upon
electrode fabrication may greatly enhance their performance. Maximilian Focke, Fabian Stumpf, Günter Roth, Roland Zengerle, Felix von StettenCentrifugal microfluidic system für primary amplification and secondary real-time PCR 2010 Lab Chip , volume : 10, pages : 3210 - 3212» show abstract « hide abstract Abstract Pre-amplification is a basis for numerous polymerase chain reaction (PCR) protocols but bears severe contamination risks due to handling of high-copy DNA samples. Therefore we developed a selfcontained centrifugal microfluidic system comprising pre-stored reagents; it enables pre-amplification of specific DNA sequences
prior to automated aliquoting and real-time PCR in a modified commercial thermocycler. Marc Karle, Junichi Miwa, Gregor Czilwik, Volker Auwärter, Günter Roth, Roland Zengerle, Felix von StettenContinuous microfluidic DNA extraction using phase-transfer magnetophoresis 2010 Lab Chip , volume : 10, pages : 3284 - 3290» show abstract « hide abstract Abstract This paper reports a novel microfluidic-chip based platform using "phase-transfer magnetophoresis"
enabling continuous biomolecule processing. As an example we demonstrate for the first time
continuous DNA extraction from cell lysate on a microfluidic chip. After mixing bacterial Escherichia
coli culture with superparamagnetic bead suspension, lysis and binding buffers, DNA is released from
cells and captured by the beads. These DNA carrying beads are continuously transported across the
interfaces between co-flowing laminar streams of sample mixture, washing and elution buffer. Bead
actuation is achieved by applying a time-varying magnetic field generated by a rotating permanent
magnet. Flagella-like chains of magnetic beads are formed and transported along the microfluidic
channels by an interplay of fluid drag and periodic magnetic entrapment. The turnover time for DNA
extraction was approximately 2 minutes with a sample flow rate of 0.75 µl/s and an eluate flow rate of
0.35 µl/s. DNA recovery was 147% (on average) compared to bead based batch-wise extraction in
reference tubes within a dilution series experiment over 7 orders of magnitude. The novel platform is
suggested for automation of various magnetic bead based applications that require continuous sample
processing, e.g. continuous DNA extraction for flow-through PCR, capture and analysis of cells and
continuous immunoassays. Potential applications are seen in the field of biological safety monitoring,
bioprocess control, environmental monitoring, or epidemiological studies such as monitoring the load
of antibiotic resistant bacteria in waste water from hospitals. L. Riegger, M.M. Mielnik, A. Gulliksen, D. Mark, J. Steigert, S. Lutz, M. Clad, R. Zengerle, P. Koltay, J. HoffmannDye-based coatings for hydrophobic valves and their application to polymer labs-on-a-chip 2010 J Micromech Microeng , volume : 20, page : 045021 » show abstract « hide abstract Abstract We provide a method for the selective surface patterning of microfluidic chips with
hydrophobic fluoropolymers which is demonstrated by the fabrication of hydrophobic valves
via dispensing. It enables efficient optical quality control for the surface patterning thus
permitting the low-cost production of highly reproducible hydrophobic valves. Specifically,
different dyes for fluoropolymers enabling visual quality control (QC) are investigated, and
two fluoropolymer-solvent-dye solutions based on fluorescent quantum dots (QD) and carbon
black (CB) are presented in detail. The latter creates superhydrophobic surfaces on arbitrary
substrates, e.g. chips made from cyclic olefin copolymer (COC, water contact angle =
157.9◦), provides good visibility for the visual QC in polymer labs-on-a-chip and increases the
burst pressures of the hydrophobic valves. Finally, an application is presented which aims at
the on-chip amplification of mRNA based on defined flow control by hydrophobic valves is
presented. Here, the optimization based on QC in combination with the Teflon-CB coating
improves the burst pressure reproducibility from 14.5% down to 6.1% compared to
Teflon-coated valves. K Seidl, S Spieth, S Herwik, J Steigert, R Zengerle, O Paul, P RutherIn-plane silicon probes for simultaneous neural recording and drug delivery 2010 J Micromech Microeng , volume : 20, pages : 105006 - (11pp)» show abstract « hide abstract Abstract This paper reports on the design, fabrication and characterization of silicon-based microprobes
for simultaneous neural recording and drug delivery. The fabrication technology is based on
two-stage deep reactive ion etching combined with silicon wafer bonding and grinding to
realize channel structures integrated in needle-like probe shafts. Liquids can be supplied to
microfluidic devices via in-plane and out-of-plane ports. The liquid is dispensed at circular
out-of-plane ports with a diameter of 25 μm and rectangular in-plane ports with dimensions of
50 × 50 μm2. Two-shaft probes with a pitch between shafts of 1.0 and 1.5 mm were realized.
The probe shafts have a length of 8 mm and rectangular cross-sections of w x h (w = 250 μm
and h = 200 or 250 μm). Each shaft contains one or two fluidic channels with a cross-section
of 50 x 50 μm2. In addition, each probe shaft comprises four recording sites with diameters
of 20 μm close to the outlet ports. Mechanical and fluidic characterization demonstrated the
functionality of the probes. Typical infusion rates of 1.5 μL min−1 are achieved at a
differential pressure of 1 kPa. The Pt-gray electrodes have an average electrode impedance of
260 ± 59 k Ohm at 1 kHz. C. Bücking, F. Popp, S. Kerzenmacher, J. GescherInvolvement and specificity of Shewanella oneidensis outer
membrane cytochromes in the reduction of soluble and solid-phase terminal electronacceptors 2010 Fems Microbiol Lett , volume : 306, pages : 144 - 151» show abstract « hide abstract Abstract The formation of outer membrane (OM) cytochromes seems to be a key step in the
evolution of dissimilatory iron-reducing bacteria. They are believed to be the
endpoints of an extended respiratory chain to the surface of the cell that establishes
the connection to insoluble electron acceptors such as iron or manganese oxides. The
gammaproteobacterium Shewanella oneidensis MR-1 contains the genetic information
for five putative OM cytochromes. In this study, the role and specificity of these
proteins were investigated. All experiments were conducted using a markerless
deletion mutant in all five OM cytochromes that was complemented via the
expression of single, plasmid-encoded genes. MtrC and MtrF were shown to be
potent reductases of chelated ferric iron, birnessite, and a carbon anode in a microbial
fuel cell. OmcA-producing cells were unable to catalyze iron and electrode reduction,
although the protein was correctly produced and oriented. However, OmcA production
resulted in a higher birnessite reduction rate compared with the mutant. The
presence of the decaheme cytochrome SO_2931 as well as the diheme cytochrome
SO_1659 did not rescue the phenotype of the deletion mutant. Sascha Lutz, Patrick Weber, Max Focke, Bernd Faltin, Jochen Hoffmann, Claas Müller, Daniel Mark, Günter Roth, Peter Munday, Niall Armes, Olaf Piepenburg, Roland Zengerle, Felix von StettenMicrofluidic lab-on-a-foil for nucleic acid analysis based on isothermal recombinase polymerase amplification (RPA) 2010 Lab Chip , volume : 10, pages : 887 - 893» show abstract « hide abstract Abstract For the first time we demonstrate a self-sufficient lab-on-a-foil system for the fully automated analysis
of nucleic acids which is based on the recently available isothermal recombinase polymerase
amplification (RPA). The system consists of a novel, foil-based centrifugal microfluidic cartridge
including prestored liquid and dry reagents, and a commercially available centrifugal analyzer for
incubation at 37 C and real-time fluorescence detection. The system was characterized with an assay
for the detection of the antibiotic resistance gene mecA of Staphylococcus aureus. The limit of detection
was <10 copies and time-to-result was <20 min. Microfluidic unit operations comprise storage and
release of liquid reagents, reconstitution of lyophilized reagents, aliquoting the sample into #30
independent reaction cavities, and mixing of reagents with the DNA samples. The foil-based cartridge
was produced by blow-molding and sealed with a self-adhesive tape. The demonstrated system excels
existing PCR based lab-on-a-chip platforms in terms of energy efficiency and time-to-result.
Applications are suggested in the field of mobile point-of-care analysis, B-detection, or in combination
with continuous monitoring systems. M. Focke, F. Stumpf, B. Faltin, P. Reith, D. Bamarni, S. Wadle, C. Müller, H. Reinecke, J. Schrenzel, P. Francois, D. Mark, G. Roth, R. Zengerle, F. von StettenMicrostructuring of polymer films for sensitive genotyping by real-time PCR on a centrifugal microfluidic platform 2010 Lab Chip , volume : 10, pages : 2519 - 2526» show abstract « hide abstract Abstract We present a novel process flow enabling prototyping of microfluidic cartridges made out of polymer
films. Its high performance is proven by implementation of a microfluidic genotyping assay testing 22
DNA samples including clinical isolates from patients infected by methicilin-resistant Staphylococcus
aureus (MRSA). The microfluidic cartridges (disks) are fabricated by a novel process called
microthermoforming by soft lithography (mTSL). Positive moulds are applied allowing for higher
moulding precision and very easy demoulding when compared to conventional microthermoforming.
High replication accuracies with geometric disk-to-disk variations of less than 1% are typical. We
describe and characterise fabrication and application of microfluidic cartridges with wall thicknesses
<188 mm thus enabling efficient thermocycling during real-time polymerase chain reaction (PCR). The
microfluidic cartridges are designed for operation in a slightly modified commercial thermocycling
instrument. This approach demonstrates new opportunities for both microfluidic developments and
well-established laboratory instruments. The microfluidic protocol is controlled by centrifugal forces
and divides the liquid sample parallely into independent aliquots of 9.8 ml (CV 3.4%, N ¼ 32 wells). The
genotyping assays are performed with pre-stored primers and probes for real-time PCR showing a limit
of detection well below 10 copies of DNA per reaction well (N ¼ 24 wells in 3 independent disks). The
system was evaluated by 44 genotyping assays comprising 22 DNA samples plus duplicates in a total of
11 disks. The samples contained clinical samples of seven different genotypes of MRSA as well as
positive and negative controls. The results are in excellent agreement with the reference in microtubes. J. Tröndle, A. Ernst, W. Streule, R. Zengerle, P. KoltayNon-contact optical sensor to detect free flying droplets in the nanolitre range 2010 Sensor Actuat A-phys , volume : 158, pages : 254 - 262» show abstract « hide abstract Abstract This paper reports on a non-contact optical sensor for the detection of single droplets in flight. The
sensor allows for online process control of non-contact dispensing systems delivering droplets in the
nanolitre range. A dispensed liquid droplet, which passes through the optical transducer, leads to a
change of the light intensity caused by absorption, reflection and diffraction. The change in light intensity
measured by a photo transistor provides information about, e.g. droplet size, velocity and shape. This
information is encoded in the time dependent signal shape that yields a characteristic “fingerprint”-
signal for each droplet. The fabrication of the sensor is achieved by standard printing circuit board (PCB)
technology. Therefore, an easy adaption of the sensor to different kinds of contactless dispensing system
and furthermore a very cost efficient production is granted. A. Hoff, A.-C. Bagu, T. André, G. Roth, K.-H. Wiesmüller, B. Gückel, R. BrockPeptide microarrays for the profiling of cytotoxic T-lymphocyte activity using minimum numbers of cells 2010 Cancer Immunol Immunother , volume : 59, pages : 1379 - 1387» show abstract « hide abstract Abstract The identification of epitopes that elicit cytotoxic
T-lymphocyte activity is a prerequisite for the
development of cancer-specific immunotherapies. However,
especially the parallel characterization of several
epitopes is limited by the availability of T cells. Microarrays
have enabled an unprecedented miniaturization and
parallelization in biological assays. Here, we developed
peptide microarrays for the detection of CTL activity.
MHC class I-binding peptide epitopes were pipetted onto
polymer-coated glass slides. Target cells, loaded with the
cell-impermeant dye calcein, were incubated on these
arrays, followed by incubation with antigen-expanded
CTLs. Cytotoxic activity was detected by release of calcein
and detachment of target cells. With only 200,000 cells per
microarray, CTLs could be detected at a frequency of 0.5%
corresponding to 1,000 antigen-specific T cells. Target
cells and CTLs only settled on peptide spots enabling a
clear separation of individual epitopes. Even though no
physical boundaries were present between the individual
spots, peptide loading only occurred locally and cytolytic
activity was confined to the spots carrying the specific
epitope. The peptide microarrays provide a robust platform
that implements the whole process from antigen presentation
to the detection of CTL activity in a miniaturized
format. The method surpasses all established methods in
the minimum numbers of cells required. With antigen
uptake occurring on the microarray, further applications are
foreseen in the testing of antigen precursors that require
uptake and processing prior to presentation. Jochen Hoffmann, Daniel Mark, Sascha Lutz, Roland Zengerle, Felix von StettenPre-storage of liquid reagents in glass ampoules for DNA extraction on a fully integrated lab-on-a-chip cartridge 2010 Lab Chip , volume : 10, pages : 1480 - 1484» show abstract « hide abstract Abstract Self-containing, ready-to-use cartridges are essential for mobile Lab-on-a-Chip (LoaC) systems intended for Point-of-Care (POC) use. Up to now, a common weak point in many LoaC developments is the need to dispense liquid reagents into the test cartridge before or during processing of the assay. To address this issue we have developed an efficient method for fusing liquid reagents into glass ampoules,
which are then sealed into a centrifugally operated cartridge. For on-demand reagent release, the
ampoules are disrupted through the flexible lid of the cartridge. Upon centrifugation, 98.7 mL out of
100 mL (CV ¼ 2.5%) of the pre-stored contents are released into the microfluidic system. No liquid loss
is observed for ethanol and H2O stored for 300 days at room temperature. Frozen storage is possible
without damage to the ampoules. Applicability of this concept is demonstrated by performing a LoaC
integrated DNA extraction after 140 days of reagent pre-storage. DNA yield from 32 mL of whole
blood was up to 199 ng, which is 77% of an off-chip reference extraction. The presented approach
allows the improvement of existing LoaC cartridges where pre-storage of liquid reagents was not
implemented yet. S. Kerzenmacher, U. Kräling, M. Schroeder, R. Brämer, R. Zengerle, F. von StettenRaney-platinum film electrodes for potentially implantable glucose fuel cells. Part 1: Nickel-free glucose oxidation anodes 2010 J Power Sources , volume : 195, pages : 6516 - 6523» show abstract « hide abstract Abstract We present a novel fabrication route yielding Raney-platinum film electrodes intended as glucose oxidation
anodes for potentially implantable fuel cells. Fabrication roots on thermal alloying of an extractable
metal with bulk platinum at 200 ◦C for 48 h. In contrast to earlier works using carcinogenic nickel, we
employ zinc as potentially biocompatible alloying partner. Microstructure analysis indicates that after
removal of extractable zinc the porous Raney-platinum film (roughness factor ∼2700) consists predominantly
of the Pt3Zn phase. Release of zinc during electrode operation can be expected to have no significant
effect on physiological normal levels in blood and serum, which promises good biocompatibility. In contrast
to previous anodes based on hydrogel-bound catalyst particles the novel anodes exhibit excellent
resistance against hydrolytic and oxidative attack. Furthermore, they exhibit significantly lower polarization
with up to approximately 100mV more negative electrode potentials in the current density range
relevant for fuel cell operation. The anodes’ amenability to surface modification with protective polymers
is demonstrated by the exemplary application of an approximately 300nm thin Nafion coating.
This had only a marginal effect on the anode long-term stability and amino acid tolerance. While in
physiological glucose solution after approximately 100 h of operation gradually increasing performance
degradation occurs, rapid electrode polarization within 24 h is observed in artificial tissue fluid. Optimization
approaches may include catalyst enhancement by adatom surface modification and the application
of specifically designed protective polymers with controlled charge and mesh size. S. Kerzenmacher, U. Kräling, M. Schroeder, R. Brämer, R. Zengerle, F. von StettenRaney-platinum film electrodes for potentially implantable glucose fuel cells. Part 2: Glucose-tolerant oxygen reduction cathodes 2010 J Power Sources , volume : 195, pages : 6524 - 6531» show abstract « hide abstract Abstract We report the fabrication and characterization of glucose-tolerant Raney-platinum cathodes for oxygen
reduction in potentially implantable glucose fuel. Fabricated by extraction of aluminum from 1µm
thin platinum–aluminum bi-layers annealed at 300 °C, the novel cathodes show excellent resistance
against hydrolytic and oxidative attack. This renders them superior over previous cathodes fabricated
from hydrogel-bound catalyst particles. Annealing times of 60, 120, and 240 min result in approximately
400–550nm thin porous films (roughness factors ∼100–150), which contain platinum and aluminum
in a ratio of ∼9:1. Aluminum release during electrode operation can be expected to have no significant
effect on physiological normal levels, which promises good biocompatibility. Annealing time has
a distinct influence on the density of trenches formed in the cathode. Higher trench densities lead to
lower electrode potentials in the presence of glucose. This suggests that glucose sensitivity is governed
by mixed potential formation resulting from oxygen depletion within the trenches. During performance
characterization the diffusion resistance to be expected from tissue capsule formation upon electrode
implantation was taken into account by placing a membrane in front of the cathode. Despite the resulting
limited oxygen supply, cathodes prepared by annealing for 60 min show more positive electrode potentials
than previous cathodes fabricated from hydrogel-bound activated carbon. Compared to operation
in phosphate buffered saline containing 3.0mMglucose, a potential loss of approximately 120mV occurs
in artificial tissue fluid. This can be reduced to approximately 90mV with a protective Nafion layer that
is easily electro-coated onto the Raney-platinum film. J. Leemhuis, E. Bouché, M. Frotscher, F. Henle, L. Hein, J. Herz, D. K. Meyer, M. Pichler, G. Roth, C. Schwan, H. H. BockReelin Signals through Apolipoprotein E Receptor 2
and Cdc42 to Increase Growth Cone Motility and
Filopodia Formation 2010 The Journal of Neuroscience , volume : 30, issue : 44, pages : 14759 - 14772» show abstract « hide abstract Abstract Lipoprotein receptor signaling regulates the positioning and differentiation of postmitotic neurons during development and modulates
neuronal plasticity in the mature brain. Depending on the contextual situation, the lipoprotein receptor ligand Reelin can have opposing
effects on cortical neurons. We show that Reelin increases growth cone motility and filopodia formation, and identify the underlying
signaling cascade. Reelin activates the Rho GTPase Cdc42, known for its role in neuronal morphogenesis and directed migration, in an
apolipoprotein E receptor 2-, Disabled-1-, and phosphatidylinositol 3-kinase-dependent manner. We demonstrate that neuronal vesicle
trafficking, a Cdc42-controlled process, is increased after Reelin treatment and further provide evidence that the peptidergic VIP/
PACAP38 system and Reelin can functionally interact to promote axonal branching. In conclusion, Reelin-induced activation of Cdc42
contributes to the regulation of the cytoskeleton of individual responsive neurons and converges with other signaling cascades to
orchestrate Rho GTPase activity and promote neuronal development. Our data link the observation that defects in Rho GTPases and
Reelin signaling are responsible for developmental defects leading to neurological and psychiatric disorders. J. D. Jeyaprakash S. Samuel, T. Brenner, O. Prucker, M. Grumann, J. Ducree, R. Zengerle, J. RüheTailormade Microfluidic Devices Through Photochemical Surface Modification 2010 Macromol Chem Phys , volume : 211, pages : 195 - 203» show abstract « hide abstract Abstract A new pathway for the generation of polymer-based microfluidic devices with tailor-made
surface chemistry is described. A simple photochemical process is used to covalently bind
polymer molecules to the surfaces of microchannels fabricated by hot embossing. The
substrates for the embossing process have the format of a compact disk (CD). CDs from
polymethylmethacrylate and polyethylene-co-norbornene were chosen due to their good
optical properties. Thin films of polymers containing photoactive benzophenone units were
deposited onto the surface of the thus generated devices. These films were subsequently
irradiated with UV light leading to the surface-attachment of ultrathin polymer networks. In
contrast to their unmodified peers, the obtained,modified
microfluidic channels coated with hydrophilic,
photoattached layers can be filled in a straightforward
manner with water by capillary forces. Channels
coated by thin films of poly(ethyloxazoline) show complete
resistance to non-specific protein binding. Generation
of hydrophobic patches inside the modified
microfluidic channels using benzophenone-containing
fluoropolymers allows the generation of passive microfluidic
valves to direct fluid motion in these CD-based
devices. F. Hedrich, K. Kliche, M. Storz, S. Billat, M. Ashauer, R. ZengerleThermal flow sensors for MEMS spirometric devices 2010 Sensors and Actuators A , volume : 162, pages : 373 - 378» show abstract « hide abstract Abstract Sleep-specific respiration disturbances and their coprevalences with basic cardiovascular diseases constitute
a supplementary risk for the cardiovascular system and require both urgent diagnostic assessment
as well as consistent therapeutic measures. Thus, the need for controlling the breathing of these patients
over a long period has become a new focus of interest. Due to its small thermal mass, the micro-machined
thermal flow sensor fits the specific requirements in the patient respiration control of high dynamic flow
range combined with a fast response time. We present the development of our flow sensor with a special
adaptation for spirometric applications. The sensor exhibits a high accuracy, a short response time
(<1 ms) and a low power consumption (10mW). Furthermore, heating structures are added onto the chip
to prevent condensation. Hence, it represents an attractive solution for the use of portable equipment for
preventive exploration of breathing in home-care applications. back to the year overview A. Ernst, W. Streule, N. Schmitt, R. Zengerle, P. KoltayA capacitive sensor for non-contact nanoliter droplet detection 2009 Sensor Actuat A-phys , volume : 153, pages : 57 - 63» show abstract « hide abstract Abstract This paper reports on a sensor for the detection of microdroplets in flight. The presented sensor is based
on a capacitive principle, which allows for non-contact monitoring of a complete droplet dispensing
process. In the presented experiments the change in capacity caused by liquid droplets in the range of
a few nanoliters passing through the electric field of the sensor is studied. From the capacitive change
the droplet presence can be deduced with a reliability of 100%, which means that every single droplet
dispensed within the experiments caused a significant signal change. In addition, the sensor signal is
sensitive to the droplet’s volume V, dielectric constant εr (epsilon) and velocity v. It turns out that every
specific droplet exhibits a characteristic “fingerprint” signal dependingonthese parameters. Especially the
droplet volume correlates very well with the peak value of the extracted signal. Therefore, the calibrated
sensor is able to determine the volume of dispensed droplets in the range from20 to 65 nl with a resolution
of less than 2 nl. Furthermore, the printed circuit board (PCB) technology applied for fabrication of the
sensor enables a very cost efficient and flexible realisation of the whole sensor unit. The non-contact
capacitive principle prevents contamination and loss of media. Therefore, the proposed approach is well
suited for high precision droplet presence detection and low cost online monitoring of liquid volumes in
microdispensing processes for various applications. S. Kerzenmacher, K. Mutschler, U. Kräling, H. Baumer, J. Ducrée, R. Zengerle, F. von StettenA complete testing environment for the automated parallel performance characterization of biofuel cells: design, validation, and application 2009 J Appl Electrochem , volume : 39, issue : 9, pages : 1477 - 1485» show abstract « hide abstract Abstract We present a complete testing environment for
the parallel performance characterization of biofuel cells.
Besides rapid-assembly electrode fixtures and an aseptic
electrochemical reactor, it comprises a 24-channel electrical
testing system that bridges the gap between simple load
resistors and costly multi-channel potentiostats. The computer-
controlled testing system features active current
control to enable the forced operation of half-cell electrodes,
whereas galvanic isolation between individual
channels ensures interference-free operation of multiple
fuel cells immersed in a common testing solution. Implemented
into the control software is an automated procedure
for the step-wise recording of polarization curves. This
way, performance overestimation due to a too fast increase
in load current can be circumvented. As an applicational
example, three abiotically catalyzed glucose fuel cells are
characterized simultaneously in a common testing solution.
Complete disclosure of the electrical system (incl. printed
circuit board layout, control software, and circuit diagrams)
in the online supplementary material accompanying this
paper allows researchers to replicate our setup in their lab
and can serve as inspiration for the design of similar systems
adapted to specific requirements. Steigert, Jürgen, Strasser, Monika, Wangler, Nicolai, Brett, Olivia, Streule, Wolfgang, Koltay, Peter, Daub, Martina, Zengerle, RolandA modular diffusion barrier based on phase separation for localized delivery of discrete drug volumes in aqueous environments 2009 Lab Chip , volume : 9, pages : 1801 - 1805» show abstract « hide abstract Abstract We present a new tool for the precisely controlled transfer of individual picoliter (pL) droplets in the
range of 150–950 pL at user defined local positions within aqueous liquid environments while avoiding
any leakage by diffusion. This is achieved by a low-cost, disposable and biocompatible cap that can be
placed on top of any pL-dispenser and generates a phase-gap between dispensing agent and target
liquid when the dispenser is dipped into the latter. We developed two different working modes: (i) the
standard mode enables an instant injection (<< 1 ms) of the droplet into the liquid environment and (ii)
the focus mode further increases the spatial resolution from 100 µm to 50 µm at the cost of slowing
down the injection time. For the phase-gap we have proven an excellent long-term stability of more
than 30 hours against capillary priming. N. Paust, Ch. Litterst, T. Metz, M. Eck, Ch. Ziegler, R. Zengerle, P. KoltayCapillary-driven pumping for passive degassing and fuel supply in direct methanol fuel cells 2009 Microfluid Nanofluid , volume : 7, pages : 531 - 543» show abstract « hide abstract Abstract In this paper we present a new concept of creating and using capillary pressure gradients for passive degassing and passive methanol supply in direct methanol fuel cells (DMFCs). An anode flow field consisting of parallel tapered channels structures is applied to achieve the passive supply mechanism. The flow is propelled by the surface forces of deformed CO2 bubbles, generated as a reaction product during DMFC operation. This work focuses on studying the influence of channel geometry and surface properties on the capillary-induced liquid flow rates
at various bubbly gas flow rates. Besides the aspect ratios
and opening angles of the tapered channels, the static contact angle as well as the effect of contact angle hysteresis has been identified to significantly influence the liquid flow rates induced by capillary forces at the bubble menisci.
Applying the novel concept, we show that the liquid flow
rates are up to thirteen times higher than the methanol
oxidation reaction on the anode requires. Experimental
results are presented that demonstrate the continuous
passive operation of a DMFC for more than 15 h. Daniel Mark, Tobias Metz, Stefan Haeberle, Sascha Lutz, Jens Ducrée, Roland Zengerle, Felix von StettenCentrifugo-Pneumatic Valve for Metering of Highly Wetting Liquids on Centrifugal Microfluidic Platforms 2009 Lab Chip , volume : 9, pages : 3599 - 3603» show abstract « hide abstract Abstract We designed and experimentally validated a new type of passive valve for centrifugal microfluidic platforms. A liquid column entering an unvented receiving chamber is stopped by the counter-pressure of compressed air. This valve opens under defined conditions at high centrifugal frequencies at which the interface between liquid and air becomes unstable and enables a phase exchange, forwarding the liquid. Burst frequencies of the valve were determined for liquids typically used in biochemical assays: pure water, water with detergent concentrations between 0.01 % and 10 %, and pure ethanol. Burst frequencies between 8.5 ± 0.6 Hz and 27.9 ± 2.0 Hz were measured for different surface tensions. The burst frequencies can be tuned by simple geometrical changes in the valving structure. The valve does not require ultra-precise structures or local surface modifications and is therefore ideal for low-cost microfluidic polymer disks. Potential applications are in the field of mulitparameter- and panel analysis, such as PCR-genotyping. Mark, Daniel, Haeberle, Stefan, Zengerle, Roland, Ducree, Jens, Vladisavljevic, Goran T.Manufacture of chitosan microbeads using centrifugally driven flow of gel-forming solutions through a polymeric micronozzle 2009 J Colloid Interf Sci , volume : 336, pages : 634 - 641» show abstract « hide abstract Abstract A centrifugally driven pulse-free flow was used for the generation of uniform chitosan beads tunable in diameter between 148 and 257 µm. The 2 % chitosan solution was extruded through a polymeric nozzle and the drops were gelated in 10 % tripolyphosphate (TPP) solution at pH 4.0. The coefficient of variation (CV) of the bead diameters issued from different nozzles could be reduced to 15 %.The production process requires a single motor as the sole actively actuated component. The production rate was 45 beads per second with one nozzle spinning at 44 Hz, scaling with the sixth power of the rotational frequency. An analytical model for the bead diameter and production rate is presented and validated by the experimental data. The shrinkage of chitosan drops during gelation was estimated from the observations and the theoretical model.
Keywords: microbeads, chitosan, centrifugal, encapsulation, microfluidics Katrin Bürk, Marie-Louise Farecki, Georg Lamprecht, Guenter Roth, Patrice Decker, Michael Weller, Hans-Georg Rammensee, Wolfang OertelNeurological Symptoms in Patients with Biopsy Proven Celiac Disease 2009 Movement Disord , volume : 24, issue : 26, pages : 2358 - 2362» show abstract « hide abstract Abstract In celiac disease (CD), the gut is the typical manifestation
site but atypical neurological presentations are
thought to occur in 6 to 10% with cerebellar ataxia being the
most frequent symptom. Most studies in this field are focused
on patients under primary neurological care. To exclude such
an observation bias, patients with biopsy proven celiac disease
were screened for neurological disease. A total of 72
patients with biopsy proven celiac disease (CD) (mean age
51 6 15 years, mean disease duration 8 6 11 years) were
recruited through advertisements. All participants adhered to
a gluten-free diet. Patients were interviewed following a
standard questionnaire and examined clinically for neurological
symptoms. Medical history revealed neurological disorders
such as migraine (28%), carpal tunnel syndrome (20%),
vestibular dysfunction (8%), seizures (6%), and myelitis
(3%). Interestingly, 35% of patients with CD reported of a
history of psychiatric disease including depression, personality
changes, or even psychosis. Physical examination yielded
stance and gait problems in about one third of patients that
could be attributed to afferent ataxia in 26%, vestibular dysfunction
in 6%, and cerebellar ataxia in 6%. Other motor features
such as basal ganglia symptoms, pyramidal tract signs,
tics, and myoclonus were infrequent. 35% of patients with
CD showed deep sensory loss and reduced ankle reflexes in
14%. Gait disturbances in CD do not only result from cerebellar
ataxia but also from proprioceptive or vestibular
impairment. Neurological problems may even develop despite
strict adherence to a gluten-free diet. Paust, N, Krumbholz, S, Munt, S, Müller, C, Koltay, P, Zengerle, R, Ziegler, CSelf-Regulating Passive Fuel Supply for Small Direct Methanol Fuel Cells Operating in All Orientations 2009 J Power Sources , volume : 192, pages : 442 - 450» show abstract « hide abstract Abstract A microfluidic fuel supply concept for passive and portable Direct Methanol Fuel Cells (DMFCs) that operate in all spatial orientations is presented. The concept has been proven by fabricating and testing a passive DMFC prototype. Methanol transport at the anode is propelled by the surface energy of deformed carbon dioxide bubbles, generated as a reaction product during DMFC operation. The experimental study reveals that in any orientation, the proposed pumping mechanism transports at least 3.5 times more methanol to the reactive area of the DMFC than the stoichiometry of the methanol oxidation would require to sustain DMFC operation. Additionally, the flow rates closely follow the applied electric load; hence the pumping mechanism is self-regulating. Oxygen is supplied to the cathode by diffusion and the reaction product water is transported out of the fuel cell along a continuous capillary pressure gradient. Results are presented that demonstrate the continuous passive operation for more than 40 hours at ambient temperature with a power output of p = 4 mW cm-2 in the preferred vertical orientation and of p = 3.2 mW cm-2 in the least favourable horizontal orientation with the anode facing downwards.
Keywords: passive DMFC; self-regulating fuel supply; capillary-force-driven bubble pump Thomas Steiner, Claudio Cupelli, Roland Zengerle, Mark SanterSimulation of advanced microfluidic systems with dissipative particle dynamics 2009 Microfluid Nanofluid , volume : 7, issue : 3, pages : 307 - 323 Jochen Rupp, Manuela Schmidt, Bettina Günther, Michael Stumber, Sven Zinober, Roland Müller-Fiedler, Bashir Alabsi, Peter Rothacher, Claas Müller, Holger Reinecke, Roland Zengerle, Martina DaubThe Way to High Volume Fabrication of Lab-on-a-Chip Devices – A Technological Approach for Polymer Based Microfluidic Systems with Integrated Active Valves and Pumps 2009 J Electron Packaging , volume : 6, pages : 1 - 7 Steinert C.P., Kalkandjiev, K., Zengerle, R., Koltay, P.TopSpot® Vario: a novel microarrayer system for highly
flexible and highly parallel picoliter dispensing 2009 Biomed Microdevices , volume : 11, issue : 4, pages : 755 - 761» show abstract « hide abstract Abstract The standard TopSpot® technology has been
successfully used in the recent years for the highly parallel
nanoliter dispensing of bio-chemical substances for microarray
printing. It is based on a pneumatically actuated
printhead which enables non-contact microarray fabrication
at a pitch of typically 500 μm. This paper reports on a new
and improved way of operating the printheads termed
TopSpot® Vario technology, using an incompressible
material between the piezo actuator and the dispensing
medium. The advantage of the incompressible medium is
the direct relation between the displacement amplitude and
the ejected liquid volume. Earlier reports stated that the
filling of the printheads is a key issue. In this paper we
report on the implementation and characterization of a new
printhead design including microchannels for bubble free
priming of blind channels. Microarray fabrication was
successfully conducted with four different types of protein. C. Ziegler, D. GerteisenValidity of two-phase polymer electrolyte membrane fuel cell models with respect to the gas diffusion layer 2009 J Power Sources , volume : 188, issue : 1, pages : 184 - 191» show abstract « hide abstract Abstract A dynamic two-phase model of a proton exchange membrane fuel cell with respect to the gas diffusion layer (GDL) is presented and compared with chronoamperometric experiments. Very good agreement between experiment and simulation is achieved for potential step voltammetry (PSV) and sine wave testing (SWT). Homogenized two-phase models can be categorized in unsaturated flow theory (UFT) and multiphase mixture (M2) models. Both model approaches use the continuum hypothesis as fundamental assumption. Cyclic voltammetry experiments show that there is a deterministic and a stochastic liquid transport mode depending on the fraction of hydrophilic pores of the GDL. ESEM imaging is used to investigate the morphology of the liquid water accumulation in the pores oftwo different media (unteflonated Toray-TGP-H-090 and hydrophobic Freudenberg H2315 I3). The morphology of the liquid water accumulation are related with the cell behavior. The results show that UFT and M2two-phase models are a valid approach for diffusion media with large fraction of hydrophilic pores such as unteflonated Toray-TGP-H paper. However, the use of the homgenized UFT and M2 models appears to be invalid for GDLs with large fraction of hydrophobic pores that corresponds to a high average contact angle of the GDL.
Keywords
Proton exchange membrane fuel cell;
Two-phase model;
Validity;
GDL back to the year overview Jürgen Steigert, Olivia Brett, Claas Müller, Monika Strasser, Nicolai Wangler, Holger Reinecke, Martina Daub, Roland ZengerleA versatile and flexible low-temperature full-wafer bonding process of monolithic 3D microfluidic structures in SU-8 2008 J Micromech Microeng , volume : 18, issue : 9, pages : 1 - 8» show abstract « hide abstract Abstract We present a versatile fabrication process for the precise fabrication of embedded
three-dimensional microfluidic structures in SU-8 photoresist. The full-wafer bond process
based on a polyester (PET) handling layer enhances the previous low-temperature bonding
technology. We achieved an extremely high bond strength of 45 MPa while requiring only
small anchoring structures. Small channel structures with an aspect ratio >2 as well as wide
membranes with an aspect ratio <0.02 were successfully bonded to realize precisely defined
channel structures. Furthermore, the developed process features high yields (>80%) and
enables the integration of microelectronics. The flexibility of the fabrication process is
presented in two contrary applications. A completely freestanding and transparent SU-8 foil
with a thickness of 225 μm featuring embedded 3D microchannels was fabricated. Also, high
quality ink-jet dispensers were successfully fabricated whereas the dispenser quality mainly
depends on the channel quality. S. Haeberle, L. Naegele, R. Burger, F. von Stetten, R. Zengerle, J. DucréeAlginate bead fabrication and encapsulation of living cells under centrifugally induced artificial gravity conditions 2008 J Microencapsul , volume : 25, issue : 4, pages : 267 - 274» show abstract « hide abstract Abstract We present a novel method for the direct, centrifugally induced fabrication of small, Ca2+-hardened alginate beads at polymer-tube micronozzles. The bead diameter can arbitrarily be adjusted between 180 µm and 800 µm by the nozzle geometry and spinning frequencies between 5 Hz and 28 Hz. The size distribution of the main peak features a CV of 7 – 16%, only. Up to 600 beads per second and channel are issued from the micronozzle through an air gap towards the curing agent contained in a standard lab tube (“Eppi”). Several tubes can be mounted on a “flying bucket” rotor where they align horizontally under rotation and return to a vertical position as soon as the rotor is at rest. The centrifugally induced, ultra-high artificial gravity conditions (up to 180 g) even allow the micro-encapsulation of alginate solutions displaying viscosities up to 50 Pa s, i.e. about 50,000 times the viscosity of water! With this low cost technology for micro encapsulation, HN25 and PC12 cells have successfully been encapsulated while maintaining vitality. Kerzenmacher S, Ducree J, Zengerle R, von Stetten FAn Abiotically Catalyzed Glucose Fuel Cell for Powering Medical Implants: Reconstructed Manufacturing Protocol and Analysis of Performance 2008 J Power Sources , volume : 182, issue : 1, pages : 66 - 75» show abstract « hide abstract Abstract Although the first abiotically catalyzed glucose fuel cells have already been developed as sustainable power supply for medical implants in the 1970s, no detailed information concerning the fabrication of these devices has been published so far. Here we present a comprehensive manufacturing protocol for such a fuel cell, together with a detailed analysis of long-term stability performance in neutral buffer containing physiological amounts of glucose and oxygen. In air saturated solution a power density of (3.3 +/- 0.2) µW cm-2 is displayed after 10 days of operation, that gradually decreases to a value of (1.0 +/- 0.05) µW cm-2 in the course of 224 days. A novelty of this work is the characterization of fuel cell performance with individually resolved electrode potentials. Using this technique, we can show that the major part of performance degradation originates from a positive shift of the anode potential, indicating that a more poisoning resistant glucose oxidation catalyst would improve the degradation behavior of the fuel cell. As further factors influencing performance an incomplete reactant separation and a mass transfer governed cathode reaction under the relatively low oxygen partial pressures of body tissue have been identified. Consequently we propose an oxygen depleting electrode interlayer and the application of more effective oxygen reduction catalysts as promising strategies to further improve the fuel cell performance under physiological concentrations of glucose and oxygen. M. Daub, R. ZengerleBioprinting on Chip 2008 Encyclopedia of Microfluidics and Nanofluidics , pages : 124 - 138 Glatzel T, Cupelli C, Lindemann T, Litterst C, Moosmann C, Niekrawietz R, Streule W, Zengerle R, Koltay PComputational fluid dynamics (CFD) software tools for microfluidic applications - A case study 2008 Comput Fluids , volume : 37, issue : 3, pages : 218 - 235 Claudio Cupelli, Björn Henrich, Thomas Glatzel, Roland Zengerle, Michael Moseler, Mark SanterDynamic capillary wetting studied with dissipative particle dynamics 2008 New Journal of Physics , volume : 10, page : 043009» show abstract « hide abstract Abstract We present a study on dynamic capillary wetting in the framework of dissipative particle dynamics (DPD) based on a novel wall model for wetting on solid boundaries. We consider capillary impregnation of a slit pore in two
situations: (i) forced (piston-driven) steady state flow and (ii) capillarity driven imbibition out of a finite reservoir. The dynamic contact angle behavior under
condition (i) is consistent with the hydrodynamic theories of Cox under partial wetting conditions and Eggers for complete wetting. The flow field near the contact line shows a region of apparent slip flow which provides a natural way
of avoiding a stress singularity at the triple line. The dynamics of the capillary imbibition, i.e. condition (ii), is consistently described by the Lucas–Washburn
equation augmented by expressions that account for inertia and the influence of the dynamic contact angle. Diana Hodgins, Arnaud Bertsch, Nils Post, Manfred Frischholz, Bart Volckaerts, John Spensley, J.M. Wasikiewicz, Henry Higgins, Felix von Stetten, Laurence KenneyHealthy Aims: Developing New Medical Implants and Diagnostic Equipment 2008 Pervasive Computing , volume : 7, issue : 1, pages : 14 - 21 J. Hermann, C. ZieglerModeling the Dynamic Water Transport in the Porous Layers
of PEM Fuel Cells Based on Numerical Upscaling 2008 J Electrochem Soc , volume : 155, issue : 10, pages : B1066 - B1076 Billat,S., Kliche,K., Gronmaier,R, Nommensen,P., Auber,J., Hedrich,F., Zengerle,R.Monolithic integration of micro-channel on disposable flow sensors for medical applications 2008 Sensors and Actuators A , volume : 145-146, pages : 66 - 74 T. Metz, J. Viertel, C. Müller, S. Kerzenmacher, N. Paust, R. Zengerle, P. KoltayPassive water management for µfuel-cells using capillary microstructures 2008 J Micromech Microeng , volume : 18, issue : 10» show abstract « hide abstract Abstract In this work we present a novel system for the passive water management in polymer electrolyte fuel cells (PEMFC) based on capillary effects in microstructures. The system removes abundant water that occurs at low temperatures at a fuel cell cathode and secures the humidity of the electrolyte membrane on higher temperatures. Liquid water is removed by hydrophilic gas supply channels with a tapered cross section as presented previously, and further transported by a system of capillary channels and a layer of nonwoven material. To prevent the membrane from running dry, a storage area in the nonwoven layer is introduced, controlled by a novel passive capillary overflow valve. The valve controls whether water is stored or finally disposed by gravity and evaporation. Experiments in a model system show that the nonwoven material is capable of removing all liquid water that can be produced by the fuel cell. A miniaturized fuel cell utilizing the novel water removal system was fabricated and experiments show that the system can stabilize the performance during changes of electrical load. Clearing the drowned miniaturized fuel cell flow field was proven and required 2 min. To make the capillary effects available for the originally hydrophobic graphite composite materials that were used to fabricate the flow fields, hydrophilic grafting based on photochemistry was applied to the material and contact angles of about 40° could be achieved and preserved for at least three months. Tobias Metz, Wolfgang Streule, Roland Zengerle, Peter KoltayStarTube: A tube with reduced contact line for minimized gas bubble resistance 2008 Langmuir , volume : 24, issue : 17, pages : 9204 - 9206» show abstract « hide abstract Abstract In this work we introduce a novel tubing design for multiphase flow that minimizes gas bubble resistance. The design
termed “StarTube” has a lamella-like wall structure and was developed to prevent clogging by gas bubbles. This is
performed by forcing gas bubbles into the center of the tube by capillary forces, allowing liquid to bypass in the outer
grooves. It was found that the mobility of gas bubbles in such a tube is increased more than 1 order of magnitude.
The reason is that the contact line perpendicular to the direction of flow is minimized, reducing resistant effects related
to the contact linesin particular, contact angle hysteresis. C. Litterst, T. Metz, R. Zengerle, P. KoltayStatic and dynamic behaviour of gas bubbles in T-shaped non-clogging micro-channels 2008 Microfluid Nanofluid , volume : 5, issue : 6, pages : 775 - 784» show abstract « hide abstract Abstract Preventing micro-channels from clogging is
a major issue in most micro and nanofluidic systems.
The T-shaped channel first reported by
Kohnle et al. prevents micro-channels from
clogging by the aid of the equilibrium bubble position in
such a geometry. This work is concerned with the static
and dynamic behaviour of bubbles in such T-shaped microchannels.
The aspect ratio of a rectangle enclosing the Tshaped
channel and the contact angle of the walls are the
main parameters influencing the static and dynamic bubble
behaviour. It is investigated in this article how these
parameters relate to the equilibrium bubble shape and how
optimum bubble velocities can be achieved inside the
channel. An analytical model depending on the contact
angle and the channel geometry is presented that allows to
determine the bubble configuration inside the channel by
minimizing the bubble’s surface energy. A second model is
derived to predict the velocity of gas bubbles driven by
buoyancy in vertical T-shaped channels. The model is
applied to design T-shaped channels with a maximum
mobility of gas bubbles. Experiments with MEMS fabricated
devices and CFD simulations are used to verify the
models. Furthermore design rules for an optimum nonclogging
channel geometry which provides the highest gas
bubble mobility are given.
Keywords Gas bubble, Micro-channel, Clogging, Interfacial energy back to the year overview Björn Henrich, Claudio Cupelli, Michael Moseler, Mark SanterAn adhesive DPD wall model for dynamic wetting 2007 Europhys Lett , volume : 80, page : 60004» show abstract « hide abstract Abstract A novel method for the treatment of solid-liquid interfaces in the framework of dissipative particle dynamics (DPD) is presented. The solid is represented by an amorphous, thermally rough ensemble of particles. Since the density of this phase is chosen commensurate to the liquid, artefacts of alternative wall models such as particle layering or spurious variations in temperature are avoided. An adjustable static contact angle permits the convenient study
of complex wetting phenomena. We explore the physical behaviour of this boundary model with respect to bulk Poiseuille and Couette flow as well as forced wetting and the behaviour of dynamic contact angles. Haeberle S, Zengerle R, Ducrée JCentrifugal Generation and Manipulation of Droplet Emulsions 2007 Microfluidics Nanofluidics , volume : 3, issue : 1, pages : 65 - 75 Haeberle,S., Schmitt,N., Zengerle,R., Ducrée,J.Centrifugo-Magnetic Pump for Gas-to-Liquid Sampling 2007 Sensors and Actuators A-Physical , volume : 135, issue : 1, pages : 28 - 33 Hu Min, Lindemann T, Goettsche T, Kohnle J, Zengerle R, Koltay PDiscrete Chemical Release from a Microfluidic Chip 2007 J Microelectromech S , volume : 16, issue : 4, pages : 786 - 794» show abstract « hide abstract Abstract We demonstrate a discrete chemical release method, capable of delivering picoliter volumes of chemical solutions with 100 μm of spatial resolution and 20 μs of response time. The releasing mechanism is based on the transfer of pulsed liquid plugs through a hydrophobic air chamber. A microfluidic chip consisting of such a releasing array (2 × 10) is designed and fabricated. Numerical simulation and experimental testing are performed to verify the working principle. Advantages of this release-on-demand technology include leakage-free, fast response and versatile control of release profile. This new method could be a key enabling technology for precisely controlled release of biochemicals for modern pharmacological and biological research.
Index Terms: Air gap, discrete chemical stimulation, microfluidic chip, picoliter chemical release, pulsed liquid ejection. Steigert,J., Brenner,T., Grumann,M., Riegger,L., Lutz,S., Zengerle,R., Ducree,J.Integrated siphon-based metering and sedimentation of whole blood on a hydrophilic lab-on-a-disk 2007 Biomed.Microdevices , issue : 9, pages : 675 - 679 Zibek S, Stett A, Koltay P, Hu M, Zengerle R, Nisch W, Stelzle MLocalized functional chemical stimulation of TE 671 cells cultured on nanoporous membrane by calcein and acetylcholine 2007 Biophys J , volume : 92, issue : 1, pages : L04 - 6L» show abstract « hide abstract Abstract Acetylcholine sensitive TE 671 cells were cultured on nanoporous membranes and chemically stimulated by localized application of i), calcein-AM and ii), acetylcholine, respectively, onto the bottom face of the membrane employing an ink jet print head. Stimulus correlated response of cells was recorded by fluorescence microscopy with temporal and spatial resolution. Calcein fluorescence develops as a result of intracellular enzymatic conversion of calcein-AM, whereas Ca2+ imaging using fluo-4 dye was employed to visualize cellular response to acetylcholine stimulation. Using 25 pl droplets and substance concentration ranging from 10 µM to 1 mM on Nucleopore membranes with pore diameters between 50 nm and 1 µm, a resolution on the order of 50 µm was achieved. Haeberle,S., Zengerle,R.Microfluidic platforms for lab-on-a-chip applications 2007 Lab Chip , volume : 7, pages : 1094 - 1110» show abstract « hide abstract Abstract We review microfluidic platforms that enable the miniaturization, integration and automation of
biochemical assays. Nowadays nearly an unmanageable variety of alternative approaches exists
that can do this in principle. Here we focus on those kinds of platforms only that allow
performance of a set of microfluidic functions—defined as microfluidic unit operations—which
can be easily combined within a well defined and consistent fabrication technology to implement
application specific biochemical assays in an easy, flexible and ideally monolithically way. The
microfluidic platforms discussed in the following are capillary test strips, also known as lateral
flow assays, the ‘‘microfluidic large scale integration’’ approach, centrifugal microfluidics, the
electrokinetic platform, pressure driven droplet based microfluidics, electrowetting based
microfluidics, SAW driven microfluidics and, last but not least, ‘‘free scalable non-contact
dispensing’’. The microfluidic unit operations discussed within those platforms are fluid transport,
metering, mixing, switching, incubation, separation, droplet formation, droplet splitting, nL and
pL dispensing, and detection. Lindemann,T., Ashauer,H., Duccio,Y.Y., Sassano,S., Zengerle,R., Koltay,P.One Inch Thermal Bubble Jet Printhead With Laser Structured Integrated Polyimide Nozzle Plate 2007 Journal of Microelectromechanical Systems , volume : 16, issue : 2, pages : 420 - 428 Metz,T., Paust,N., Müller,C., Zengerle,R., Koltay,P.Passive water removal in fuel cells by capillary droplet actuation 2007 Sensors & Actuators: A.Physical , volume : Special Issue MEMS 2007 Steigert J, Haeberle S, Brenner T, Mueller C, Steinert C P, Koltay P, Gottschlich N, Reinecke H, Ruehe J, Zengerle R, Ducrée JRapid prototyping of microfluidic chips in COC 2007 J Micromech Microeng , volume : 17, pages : 333 - 341 L. Riegger, M. Grumann, J. Steigert, S. Lutz, C.P. Steinert, C. Mueller, J. Viertel, O. Prucker, J. Rühe, R. Zengerle, J. DucreeSingle-step centrifugal hematocrit determination on a 10-$ processing device 2007 Biomed Microdevices , volume : 9, pages : 795 - 799» show abstract « hide abstract Abstract We present a novel concept to process human
blood on a spinning polymer disk for the determination of
the hematocrit level by simple visual inspection. The
microfluidic disk which is spun by a macroscopic drive
unit features an upstream metering structure and a
downstream blind channel where the centrifugally enforced
sedimentation of the blood is performed. The bubble-free
priming of the blind channel is governed by centrifugally
assisted capillary filling along the sloped hydrophilic sidewall
and the lid as well as the special shape of the dead
end of the two-layer channel. The hematocrit is indicated
at the sharp phase boundary between the plasma and the
segregated cellular pellet on a disk-imprinted calibrated
scale. This way, we conduct the hematocrit determination
of human blood within 5 min at a high degree of linearity
(R2=0.999) and at a high accuracy (CV=4.7%) spanning
over the physiological to pathological working range. As
all processing steps including the priming, the metering to
a defined volume as well as the centrifugation are executed
automatically during rotation, the concept is successfully
demonstrated in a conventional PC-CDROM drive while
delivering the same performance (R2=0.999, CV=4.3%). back to the year overview Messner S, Schaible J, Sandmaier H, Zengerle R3-way silicon microvalve for pneumatic applications with electrostatic actuation principle 2006 Microfluidics and Nanofluidics , issue : 2, pages : 89 - 96 Haeberle S, Brenner T, Zengerle R, Ducree JCentrifugal extraction of plasma from whole blood on a rotating disk 2006 Lab on A Chip , volume : 6, issue : 6, pages : 776 - 781 Steigert J, Grumann M, Dube M, Streule W, Riegger L, Brenner T, Koltay P, Mittmann K, Zengerle R, Ducrée JDirect Hemoglobin Measurement on a Centrifugal Microfluidic Platform for Point-of-Care Diagnostics 2006 Sensors and Actuators , pages : 228 - 233 Steigert J, Grumann M, Brenner T, Riegger L, Harter J, Zengerle R, Ducrée JFully Integrated Whole Blood Testing by Real-Time Absorption Measurement on a Centrifugal Platform 2006 Lab Chip , volume : 6, issue : 8, pages : 1040 - 1044 Litterst C, Eccarius S, Hebling C, Zengerle R, Koltay PIncreasing µDMFC efficiency by passive CO2 bubble removal and discontinuous operation 2006 Journal of Micromechanics and Microengineering , volume : 16, issue : 9, pages : S248 - S253 Boettcher M, Jaeger M S, Riegger L, Ducrée J, Zengerle R, Duschl CLab-on-chip-based cell separation by combining dielectrophoresis and centrifugation 2006 Biophysical Reviews & Letters , volume : 1, issue : 4, pages : 443 - 451 Ducrée J, Brenner T, Haeberle S, Glatzel T, Zengerle RMultilamination of flows in planar networks of rotating microchannels 2006 Microfluidics and Nanofluidics , volume : 2006, issue : 2, pages : 78 - 84 Ducrée J, Zengerle R, Grumann M, Brenner TOne Droplet of Blood Lab-on-a-Chip System for Rapid Diagnostic 2006 G.I.T Laboratory Journal , volume : 1, pages : 34 - 36 Ducrée J, Haeberle S, Brenner T, Glatzel T, Zengerle RPatterning of flow and mixing in rotating radial microchannels 2006 Microfluidics and Nanofluidics , volume : 2, issue : 2, pages : 97 - 105 Riegger L, Grumann M, Nann T, Riegler J, Ehlert O, Mittenbühler K, Urban G, Pastewka L, Brenner T, Zengerle R, Ducrée JRead-out Concepts for Multiplexed Bead-based Fluorescence Immunoassays on Centrifugal Microfluidic Platforms 2006 Sensors and Actuators A-Physical , volume : 126, pages : 455 - 462 Grumann M, Steigert J, Riegger L, Moser I, Enderle B, Riebeseel K, Urban G, Zengerle R, Ducree JSensitivity enhancement for colorimetric glucose assays on whole blood by on-chip beam-guidance 2006 Biomed Microdevices , pages : 209 - 214 back to the year overview Grumann M, Geipel A, Riegger L, Zengerle R, Ducrée JBatch-mode mixing on centrifugal microfluidic platforms 2005 Lab on A Chip , volume : 5, issue : 5, pages : 560 - 565 Haeberle S, Brenner T, Schlosser HP, Zengerle R, Ducrée JCentrifugal micromixer 2005 Chemical Engineering & Technology , volume : 28, issue : 5, pages : 613 - 616 Gutmann O, Kuehlewein R, Reinbold S, Niekrawietz R, Steinert CP, de Heij B, Zengerle R, Daub MFast and reliable protein microarray production by a new drop-in-drop technique 2005 Lab on A Chip , volume : 5, issue : 6, pages : 675 - 681 Brenner T, Glatzel T, Zengerle R, Ducrée JFrequency-dependent transversal flow control in centrifugal microfluidics 2005 Lab on A Chip , volume : 5, issue : 2, pages : 146 - 150 Steigert J, Grumann M, Brenner T, Mittenbühler K, Nann T, Rühe J, Moser I, Haeberle S, Riegger L, Riegler J, Bessler W, Zengerle R, Ducrée JIntegrated Sample Preparation, Reaction, and Detection on a High-frequency Centrifugal Microfluidic Platform 2005 Journal of the Association for Laboratory Automation (JALA) , volume : 10, issue : 5, pages : 331 - 341 Zengerle RMicro- and Nano Cluster Freiburg 2005 mst-news , volume : 6, page : 38 Jeyaprakash JDS, Steger R, Birkle G, Zengerle R, Koltay P, Ruehe JModification of Micronozzle Surfaces Using Fluorinated Polymeric Nanofilms for Enhanced Dispensing of Polar and Nonpolar Fluids 2005 Analytical Chemistry , volume : 77, issue : 19, pages : 6469 - 6474 Kaack R, Dankbar D, Müller-Chorus B, Jung A, Daub MModulare Plattform mit integrierter Nanoliterdosierung 2005 Laborwelt , volume : 6, issue : 2, pages : 10 - 13» show abstract « hide abstract Abstract Im Bereich der Genom-Forschung sind in den letzten Jahren erhebliche Fortschritte erzielt worden. Möglich wurden diese durch innovative Entwicklungen in der Automatisierung und Mikrofluidik, die als Schlüsselgebiete für die moderne Biotechnologie betrachtet werden können. Ein Beispiel dafür sind die ersten kommerziellen Ansätze zur hochparallelen Expressionsanalyse in miniaturisierten Formaten. Der nächste Schritt, der zwangsläufig folgen muss, sind Weiterent wicklungen hinsichtlich Quantifizierbarkeit (Sensitivität und Selektivität), Schnelligkeit (Parallelität) und Modularität, so dass mit nur einer Geräteplattform eine Vielzahl möglicher Anwendungen, wie z.B. die routinemäßige Diagnostik von SNPs (single nucleotide polymorphisms) oder die Identifikation und Validierung neuer Rezeptoren in der Wirkstoff-Forschung kostengünstig erschlossen werden können. Bohl B, Steger R, Zengerle R, Koltay PMulti-layer SU-8 Lift-Off Technology For Microfluidic Devices 2005 Journal of Micromechanics and Microengineering , volume : 15, pages : 1125 - 1130 Goettsche T, Kohnle J, Willmann M, Ernst H, Spieth S, Tischler R, Messner S, Zengerle R, Sandmaier HNovel approaches to particle tolerant valves for use in drug delivery systems 2005 Sensors and Actuators A-Physical , volume : 118, issue : 1, pages : 70 - 77 Ducrée J, Zengerle R, Grumann M, Brenner TSchnelle Diagnose aus einem Tropfen Blut 2005 Mikrosystemtechnik , volume : 3 Daub MTopSpot Quality Microarrays 2005 Labor Medizin & Diagnostik , pages : 25 - 26» show abstract « hide abstract Abstract TopSpot® technology introduces a new concept into the microarray laboratory: highly parallel non-contact dispensing of bioanalytical reagents for the production of low to medium density microarrays. The technology is based on micromachined multi-channel printheads combined with a piezo-driven droplet ejection process. Different automation environments for these print modules allow TopSpot® technology to cover needs from decentralized laboratories to core facilities Grumann M, Brenner T, Beer C, Zengerle R, Ducrée JVisualization of flow patterning in high-speed centrifugal microfluidics 2005 Review of Scientific Instruments , volume : 76, issue : 2, pages : 025101 - 025101 back to the year overview Gutmann O, Kuehlewein R, Reinbold S, Niekrawietz R, Steinert CP, De HB, Zengerle R, Daub MA highly parallel nanoliter dispenser for microarray fabrication 2004 Biomed Microdevices , volume : 6, issue : 2, pages : 131 - 137» show abstract « hide abstract Abstract We report about the correlation between satellite free droplet release and liquid viscosity in a highly parallel, pressure driven nanoliter dispenser. In extensive studies we found that for liquids of different viscosities the duration of the pressure pulse is the predominant effect compared to pressure amplitude. This result is of essential importance when actuation parameters have to be adopted for different media like oligonucleotide, DNA or protein solutions as it is the case for the non contact high throughput fabrication of microarrays (Ducree et al., 2000). Experiments with oligonucleotides as well as with different proteins showed ascertained carry-over and cross-contamination free printing of DNA and protein microarrays. With it a prime critical point of microarray production is solved, leading to high quality whilst high throughput microarray fabrication. For oligonucleotides printing we found CVs to be better than 1% within one single dispensing channel and 1.5 % within all 24 channels of a 24 channel printhead for each used printing buffer. By optimizing the protein printing buffer the CVs for protein printing were reduced to about 1% within all 24 channels. As a serious practical application test oligonucleotides microarrays were produced using our nanoliter dispenser system. With it a full DNA hybridization experiment was performed. Clear positive signals one hand and no signals in the negative controls on the other hand showed that our system is suited for microarray production. Steinert CP, Goutier I, Gutmann O, Sandmaier H, Daub M, de Heij B, Zengerle RA highly parallel picoliter dispenser with an integrated, novel capillary channel structure 2004 Sensors and Actuators A-Physical , volume : 116, issue : 1, pages : 171 - 177» show abstract « hide abstract Abstract We present a cross-contamination free highly-parallel picoliter dispenser based on direct liquid displacement. Such dispensers are essential for the (mass) fabrication of microarrays [J. Ducrée, H. Gruhler, N. Hey, M. Mueller, S. Békési, M. Freygang, H. Sandmaier, R. Zengerle, TopSpota new method for the fabrication of microarrays, Tech. Digest, The Thirteenth IEEE Annual International Conference on Micro Electro Mechanical Systems, Mizyazaki, Japan, 2327 January 2000, pp. 317322] and are able to dispense up to 384 different reagents at a pitch of 500 µm simultaneously [A. Kuoni, M. Boillat, N.F. de Rooij, A highly parallel piezoelectric printing device for microarray technology, Tech. Digest, The 17th International Conference on Micro Electro Mechanical Systems, Maastricht, The Netherlands, 2529 January 2004, pp. 466469]. In contrast to an earlier design [Sens. Actuators A 103 (2003) 88] we investigated different nozzle diameters and a novel capillary channel design.We present a systematic study concerning the relation between nozzle diameter and ejected droplet volume. The change from 35 to 60 µm in nozzle diameter resulted in a doubling of dispensed volume for most used elastomers and irrespective of actuation parameters. Minimum and maximum dispensed volumes have been determined to be 125 and 1700 pl. Those results are based on a new design, which also includes passive microstructures for droplet homogeneity as well as modified microchannels for improved priming and prevention of cross-contamination. Based on this, the coefficient of variation (CV) of droplet velocity could be reduced from 50% down to less than 5%. The CV of droplet volume is clearly below the measurement error (8%). Keywords: Picoliter dispenser; Non-contact printing; Microchannel; Microfluidics; Microarrays; Biochips Grumann M, Dobmeier M, Schippers P, Brenner T, Kuhn C, Fritsche M, Zengerle R, Ducrée JAggregation of bead-monolayers in flat microfluidic chambers simulation by the model of porous media 2004 Lab on A Chip , volume : 4, issue : 3, pages : 209 - 213» show abstract « hide abstract Abstract In this paper, we for the first time simulate the process of hydrodynamic bead aggregation in a flat micro-fluidic chamber by a porous-media model in an iterative routine. This allows us to optimize the chamber design of our recently developed experimental method to form periodical monolayers from the flow of bead suspension. Periodical monolayers are advantageous for parallel assay formats since they enhance the mechanical rigidity of the aggregated pattern. This is important to avoid a spatial rearrangement along various steps of a read-out procedure which would impair the correlation between measurements. Furthermore, the monolayer formation guarantees the individual optical accessibility of all probe beads. By modelling the monolayers with porous media, we can drastically reduce the degrees of freedom in a two-phase, multi-particle problem. This way, we are able to compute stationary hydrodynamic flow patterns in the chamber. In order to simulate the complete filling process from these stationary solutions, we developed an iterative master routine which takes the transient aggregation pattern as the initial condition, then evaluates the placement of the newly introduced beads, and finally converts the points of aggregation into porous media. de Heij B, Daub M, Gutmann O, Niekrawietz R, Sandmaier H, Zengerle RHighly parallel dispensing of chemical and biological reagents 2004 Analytical and Bioanalytical Chemistry , volume : 378, issue : 1, pages : 119 - 122 Gutmann O, Niekrawietz R, Kuehlewein R, Steinert CP, de Heij B, Zengerle R, Daub MImpact of medium properties on droplet release in a highly parallel nanoliter dispenser 2004 Sensors and Actuators A-Physical , volume : 116, issue : 2, pages : 187 - 194 Gutmann O, Niekrawietz R, Kuehlewein R, Steinert CP, Reinbold S, De HB, Daub M, Zengerle RNon-contact production of oligonucleotide microarrays using the highly integrated TopSpot nanoliter dispenser 2004 Analyst , volume : 129, issue : 9, pages : 835 - 840» show abstract « hide abstract Abstract For the first time we report on the production of oligonucleotide microarrays using a highly parallel and highly integrated, pressure driven TopSpot nanoliter dispenser. The system enables non-contact printing of different media like oligonucleotides, DNA or protein solutions. We optimized the printing buffer needed for oligonucleotides microarrays production with respect to two major aspects: microfluidical optimum for droplet dispensing and biochemical coupling efficiency on different commercially available microarray slides. Coefficient of variations (CVs) of generated spot diameters were measured to be smaller than 1% within one single dispensing nozzle and smaller than 1.5% within all 24 parallel nozzles of the printhead for all printing buffers used. No carry-over and no cross-talk was found, in extensive experiments with oligonucleotides. Optimized printing buffer compositions and concentrations for oligonucleotide microarrays were found, as well as optimized coupling protocols. Furthermore, buffers and protocols were adapted to a host of different microarray slides used. With this system, prime critical points of microarray production are solved, leading to high quality high throughput microarray fabrication. Streule W, Lindemann T, Birkle G, Zengerle R, Koltay PPipeJet: A Simple Disposable Dispenser for the Nano- and Microliter Range 2004 Journal of the Association for Laboratory Automation (JALA) , volume : 9, issue : 5, pages : 300 - 306» show abstract « hide abstract Abstract This paper reports on a simple, disposable non-contact dispenser for the nano- and microliter range. In contrast to other known dispensers manufactured by silicon micromachining the new device simply consists of an elastic polymer tube with a circular cross section. Actuation is done by a piezostack driven piston, squeezing the tube at a defined position near the open end by a significant fraction of the cross section. In contrast to drop-on-demand devices based on an acoustic actuation principle,5 the squeezing of the tube leads to a significant mechanical displacement of the liquid. Our experiments tested a large number of media in the viscosity range from 1 to 27 mPas. Some of our experiments tested up to approximately 2,000 mPas. Frequency characteristics showed an independent dosage volume for water up to a frequency of 15 Hz for tubes with an inner diameter of approximately 200 lm. Standard deviation within 1,000 shots resulted in an excellent CV (standard deviation/ dosage volume) of less than 2% of the dosage volume. Using tubes with an inner diameter of approximately 1,000 µm and a print frequency of 340 Hz, a flowrate of less than or equal to 143 µL/s could be reached. Beyond the possibility to dispense pure liquids, emulsion paints with particles that have a diameter of approximately 40 µm have also been printed successfully. Breisch S, de Heij B, Lohr M, Stelzle MSelective chemical surface modification of fluidic microsystems and characterization studies 2004 Journal of Micromechanics and Microengineering , volume : 14, issue : 4, pages : 497 - 505» show abstract « hide abstract Abstract Control of wetting behaviour of fluidic microsystems was achieved by selective chemical surface modification using either a solution-based procedure or micro-contact printing. The modification procedures were designed in such a way as to obtain optimum wetting in fluid channels, sample reservoirs and nozzles, while at the same time preventing intermixing of fluids from different nozzle exits and thus enabling multiple long-term stable delivery of nano-litre droplets. Analysis included thickness measurements by ellipsometry, contact angle measurements and fluorescence microscopy. Selectively coated TopSpot dosage chips as are used for the fabrication of DNA and protein micro-arrays exhibit superior performance over uncoated dosage chips. Mixed and back-filled silane coatings show enhanced stability versus hydrolysis in basic and acidic solutions, as has been determined from measurements of contact angle as a function of immersion time. Steger R, Bohl B, Zengerle R, Koltay PThe dispensing well plate: a novel device for nanoliter liquid handling in ultra high-throughput screening 2004 Journal of the Association for Laboratory Automation , volume : 9, issue : 5, pages : 291 - 299» show abstract « hide abstract Abstract This article reports on a novel dispensing system for the massive parallel delivery of liquid volumes in the range of 50 nL. Due to the similarity of the device to conventional micro-well plates used for the storage of liquids, the device has been termed dispensing well plate (DWP). In contrast to other known micro dispensers, the DWP can consist of up to 1,536 dispensing units in parallel, all of which hold different reagents. The dispensing units can be arranged very closely at the pitch of conventional micro-well plates (2.25 mm or 4.5 mm). Driven by pneumatic actuation, a fixed volume of different liquids can be dispensed simultaneously and contact-free into micro-well plates or onto flat substrates. Because of this, the liquid handling in many chemical, biochemical, and pharmaceutical applicationsespecially within highthroughput screening (HTS)can be sped up by a factor of 10 to 100. In our article, the basic operation principle of the device is presented, and experimental evidence of its extraordinary performance is given: a reproducibility of 2% to 5% and a homogeneity within individual droplet arrays of 1% to 2% has been measured, as well as viscosity independent performance for liquids in the range from 1 to 5 mPas. The applicability of the DWP technology within HTS is demonstrated by performing a miniaturized kinase assay at 1 lL assay volume in a 1536- well plate format. Koltay P, Steger R, Bohl B, Zengerle RThe dispensing well plate: a novel nanodispenser for the multiparallel delivery of liquids (DWP Part I) 2004 Sensors and Actuators A-Physical , volume : 116, issue : 3, pages : 483 - 491» show abstract « hide abstract Abstract This paper reports on a novel dispensing system for the massive parallel delivery of liquid volumes in the range of 50 nL. Due to the similarity of the device to conventional microwell plates used for storage of liquids, the device has been termed dispensing well plate (DWP). In contrast to other known microdispensers the DWP can consist of up to 1536 dispensing units in parallel all holding different reagents. The dispensing units can be arranged very closely at the pitch of conventional microwell plates (2.25 or 4.5 mm). Driven by pneumatic actuation a fixed volume of different liquids can be dispensed simultaneously and contact free into microwell plates or onto flat substrates. By this the liquid-handling in many chemical, biochemical and pharmaceutical applicationsespecially within high throughput screening (HTS)can be speed up by a factor 10100. In this paper the basic operation principle of the device is presented and experimental evidence is given of its extraordinary performance: a reproducibility of 25% and a homogeneity within individual droplet arrays of 12% has been measured as well as viscosity independent performance for liquids in the range from 1 to 5mPas. The fabrication of DWP prototypes by different micromachining technologies based on silicon dry etching and SU-8 technology is described and various DWP prototypes with different dosage volumes are presented.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Non-contact dispenser; Jets; High throughput screening; SU-8 Koltay P, Kalix J, Zengerle RTheoretical evaluation of the dispensing well plate method (DWP part II) 2004 Sensors and Actuators A-Physical , volume : 116, issue : 3, pages : 472 - 482» show abstract « hide abstract Abstract The dispensing well plate (DWPTM) method is a technique to deliver fluidic jets or droplets with volumes of several nanoliters contact free to targets likemicro well plates or slides. A cheap and simple pneumatic actuation mechanism allows for the simultaneous delivery of a large number of different liquids. In this paper the dispensing dynamics of a DWP-type nanodispenser is studied theoretically. The device is modelled using computational fluid dynamics (CFD) simulations which are benchmarked to experimental data. Furthermore an analytical discussion is presented providing some insight into the dispensing dynamics. Based on these modelling approaches the dispensing process is studied in detail. Influence of system parameters like driving pressure, nozzle size, channel layout etc. on the jet formation and dispensed volume are quantified and design rules are given to improve the performance.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Droplet dispensing; Jets; CFD-simulation; Microfluidics back to the year overview de Heij B, Steinert C, Sandmaier H, Zengerle RA tuneable and highly-parallel picolitre-dispenser based on direct liquid displacement 2003 Sensors and Actuators A-Physical , volume : 103, issue : 1-2, pages : 88 - 92» show abstract « hide abstract Abstract We present a new method for the highly-parallel and simultaneous delivery of a multitude of reagents in the picolitre range. This method is based on direct displacement of the liquids using an elastomer-stamp, which simultaneously actuates up to 96 dosing channels, at a pitch of 500 mm. We were able to tune droplet volume from 100 to 700 pl and droplet speed from 0.3 to 4 m/s using printheads with 50 mm diameter nozzles. In contrast to all other inkjet techniques the new direct displacement method enables the precise control of dispensing quantity in the picolitre range regardless of reagent viscosity.
© 2003 Elsevier Science B.V. All rights reserved.
Keywords: Highly-parallel; Picolitre-dispenser; Bio-molecule; Microfluidics Waibel G, Kohnle J, Cernosa R, Storz M, Schmitt M, Ernst H, Sandmaier H, Zengerle R, Strobelt THighly integrated autonomous microdosage system 2003 Sensors and Actuators A-Physical , volume : 103, issue : 1-2, pages : 225 - 230 back to the year overview Ducrée J, Zengerle RMicrofluidics - Markets and Technologies 2002 mstnews , volume : 05, issue : 02, pages : 8 - 9» show abstract « hide abstract Abstract The field of microfluidics has become one of the most dynamically emerging disciplines of microtechnology in the recent decade. Microfluidics offers the mere benefits of miniaturization enabling portable and inexpensive devices, mostly for analytical and diagnostic purposes where the costs per test can be greatly reduced. It has also become evident that microfluidics provides a unique access to the nanoworld of biomolecular chemistry thus setting the pace for many leading edge biotechnological innovations.
In the course of the FlowMap project , a consortium of European partners such as IMTEK (D), HSG-IMIT (D), Cranfield Biotechnology Center (UK), Yole Dévelopement (F) and Wicht Technology Consulting (D) has analyzed the structure of the field in terms of markets, products and technologies. This information will be the basis for an explorative technology roadmap which we develop for microfluidics in the life sciences. A time frame for the development of technological and economic landmarks will be introduced and sequences as well as dependencies will be illustrated. This will allow to plot the complete road between technologies and markets. back to the year overview Peter Koltay, Bas de Heij, Hermann Sandmaier, Roland ZengerleAutomatisiertes Liquid Handling im Nanoliterbereich 2001 Inno Innovative Technik Anwendungen aus Nordrhein-Westfalen; Nr. 19 (3/01) back to the year overview Jens Ducrée, Bas de Heij, Hermann Sandmaier, Roland ZengerleTopSpot Ein Verfahren zur
Massenproduktion von Biochips. 2000 Life Science Technologien; 6/2000 back to the year overview Zengerle RMikrosysteme - Chancen für die Dosiertechnik 1996 wägen + dosieren , volume : 1, pages : 10 - 15 Zengerle RStand der Technik bei mikrofluidischen Aktoren 1996 Feinwerktechnik und Mikrotechnik , volume : 104, pages : 241 - 248 Ulrich J, Füller H, Zengerle RStatic and dynamic flow simulation of a KOH-etched micro valve 1996 Sensors and Actuators A , volume : 53, pages : 379 - 385 Stehr M, Messner S, Sandmaier H, Zengerle RThe VAMP - A new device for handling liquids and gases 1996 Sensors & Actuators A , volume : 57, pages : 153 - 157 back to the year overview Zengerle R, Ulrich J, Kluge S, Richter M, Richter AA bidirectional silicon micropump 1995 Sensors & Actuators A , volume : 50, pages : 81 - 86 Zengerle R, Geiger W, Richter M, Ulrich J, Kluge S, Richter ATransient measurements on miniaturized diaphragm pumps in microfluidic systems 1995 Sensors & Actuators A , volume : 46-47, pages : 557 - 561 back to the year overview Zengerle, R, Richter MSimulation of microfluid systems 1994 Journal of Micromechanics and Microengineering , volume : 4, pages : 192 - 204 back to the year overview Richter A, Zengerle R, Plettner A, Sandmaier HElektrohydrodynamische Mikropumpen 1992 VDI Berichte , volume : 960, pages : 235 - 249 back to the year overview Michel-Beyerle M E, Zengerle REffect of quinone depletion on lifetime spectra in photosynthetic reaction centers 1991 Chemical Physics Letters , volume : 176, issue : 1, pages : 85 - 90
Reviews Years: 2023 |
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2007 | show all back to the top of all publications back to the year overview back to the year overview H. C. Ates, A. Brunauer, F. von Stetten, G. A. Urban, F. Güder, A. Merkoçi, S. M. Früh, C. DincerIntegrated Devices for Non‐Invasive Diagnostics 2021 Advanced Functional Materials , volume : 31, issue : 15, page : 2010388» show abstract « hide abstract Abstract “Sample‐in‐answer‐out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non‐invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non‐invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition. back to the year overview M. Trotter, N. Borst, R. Thewes, F. von StettenElectrochemical DNA sensing – Principles, commercial systems, and applications 2020 Biosens Bioelectron , volume : 154, page : 112069» show abstract « hide abstract Abstract Driven by the vision of robust and portable, yet sensitive DNA detection systems for point-of-need applications, the development of electrochemical DNA sensing principles has been of high interest. Many different principles have been developed and these are regularly reviewed. However, the maturity of electrochemical principles and their ability to produce competitive real-world applications is rarely assessed.
In this review, general electrochemical DNA sensing principles are briefly introduced and categorized into heterogeneous vs. homogeneous approaches, and then the subcategories label-free vs. labeled and reagent-less vs. reagent-dependent principles. We then focus on reviewing the electrochemical sensing principles implemented in DNA detection systems, which are commercially available or close to market entry, considering the complete analysis process, automation and the field of application. This allows us to outline and discuss which principles have proved suitable for which kinds of applications, as well as the stage of integration and automation.
Examples from all the identified categories of electrochemical DNA sensing principles have found application in commercial detection systems or advanced prototypes. Various applications have already been demonstrated, ranging from on-site skin care testing, to food safety to the most frequent in vitro diagnostic tests, partially conducted in automated sample-to-answer devices.
Our review is intended to enable researchers in areas related to electrochemistry, biochemistry or microfluidics to assess the commercial state of the art of electrochemical nucleic acid testing, and the interdisciplinary challenges for further improvements.
Download file J. F. Hess, T.A. Kohl, M. Kotrová, K. Roensch, T. Paprotka, V. Mohr, T. Hutzenlaub, M. Brüggemann, R. Zengerle, S. Niemann, N. PaustLibrary preparation for next generation sequencing: A review of automation strategies 2020 Biotechnol Adv , page : 107537» show abstract « hide abstract Abstract Next generation sequencing is in the process of evolving from a technology used for research purposes to one which is applied in clinical diagnostics. Recently introduced high throughput and benchtop instruments offer fully automated sequencing runs at a lower cost per base and faster assay times. In turn, the complex and cumbersome library preparation, starting with isolated nucleic acids and resulting in amplified and barcoded DNA with sequencing adapters, has been identified as a significant bottleneck. Library preparation protocols usually consist of a multistep process and require costly reagents and substantial hands-on-time. Considerable emphasis will need to be placed on standardisation to ensure robustness and reproducibility. This review presents an overview of the current state of automation of library preparation for next generation sequencing. Major challenges associated with library preparation are outlined and different automation strategies are classified according to their functional principle. Pipetting workstations allow high-throughput processing yet offer limited flexibility, whereas microfluidic solutions offer great potential due to miniaturisation and decreased investment costs. For the emerging field of single cell transcriptomics for example, microfluidics enable singularisation of tens of thousands of cells in nanolitre droplets and barcoding of the RNA to assign each nucleic acid sequence to its cell of origin. Finally, two applications, the characterisation of bacterial pathogens and the sequencing within human immunogenetics, are outlined and benefits of automation are discussed. back to the year overview J. Li, J. Macdonald, F. von StettenCorrection: Review: a comprehensive summary of a decade development of the recombinase polymerase amplification 2019 Analyst , volume : 144, issue : 31
Download file A. van Belkum, T. T. Bachmann, G. Lüdke, J. G. Lisby, G. Kahlmeter, A. Mohess, K. Becker, J. P. Hays, N. Woodford, K. Mitsakakis, J. Moran- Gilad, J. Vila, H. Peter, J. H. Rex, W. M. Dunne Jr., and the JPIAMR AMR-RDT Working GroupDevelopmental roadmap for antimicrobial susceptibility testing systems 2019 Nat Rev Microbiol , volume : 17, pages : 51 - 62» show abstract « hide abstract Abstract Antimicrobial susceptibility testing (AST) technologies help to accelerate the initiation of targeted antimicrobial therapy for patients with infections and could potentially extend the lifespan of current narrow-spectrum antimicrobials. Although conceptually new and rapid AST technologies have been described, including new phenotyping methods, digital imaging and genomic approaches, there is no single major, or broadly accepted, technological breakthrough that leads the field of rapid AST platform development. This might be owing to several barriers that prevent the timely development and implementation of novel and rapid AST platforms in health-care settings. In this Consensus Statement, we explore such barriers, which include the utility of new methods, the complex process of validating new technology against reference methods beyond the proof-of-concept phase, the legal and regulatory landscapes, costs, the uptake of new tools, reagent stability, optimization of target product profiles, difficulties conducting clinical trials and issues relating to quality and quality control, and present possible solutions. J. F. Hess, S. Zehnle, P. Juelg, T. Hutzenlaub, R. Zengerle, N. PaustReview on pneumatic operations in centrifugal
microfluidics
2019 Lab Chip , volume : 22, pages : 3745 - 3770» show abstract « hide abstract Abstract Centrifugal microfluidics allows for miniaturization, automation and parallelization of laboratory workflows. The fact that centrifugal forces are always directed radially outwards has been considered a main drawback for the implementation of complex workflows leading to the requirement of additional actuation forces for pumping, valving and switching. In this work, we review and discuss the combination of centrifugal with pneumatic forces which enables transport of even complex liquids in any direction on centrifugal systems, provides actuation for valving and switching, offers alternatives for mixing and enables accurate and precise metering and aliquoting. In addition, pneumatics can be employed for timing to carry out any of the above listed unit operations in a sequential and cascaded manner. Firstly, different methods to generate pneumatic pressures are discussed. Then, unit operations and applications that employ pneumatics are reviewed. Finally, a tutorial section discusses two examples to provide insight into the design process. The first tutorial explains a comparatively simple implementation of a pneumatic siphon valve and provides a workflow to derive optimum design parameters. The second tutorial discusses cascaded pneumatic operations consisting of temperature change rate actuated valving and subsequent pneumatic pumping. In conclusion, combining pneumatic actuation with centrifugal microfluidics allows for the design of robust fluidic networks with simple fluidic structures that are implemented in a monolithic fashion. No coatings are required and the overall demands on manufacturing are comparatively low. We see the combination of centrifugal forces with pneumatic actuation as a key enabling technology to facilitate compact and robust automation of biochemical analysis. J. Li, J. Macdonald, F. von StettenReview: a comprehensive summary of a decade
development of the recombinase polymerase
amplification
2019 Analyst , volume : 144, issue : 31, pages : 31 - 67» show abstract « hide abstract Abstract Nucleic acid amplification has permeated every field in the life sciences since the introduction of the
classic polymerase chain reaction (PCR) method in 1983. Yet, despite its fundamental reach, PCR has
been constrained within the walls of a laboratory, due to its requirement for a sophisticated thermocycling
machine, limiting external application in low-resource settings. New isothermal amplification strategies
are seeking to break through traditional laboratory boundaries by providing nucleic acid replication at
constant temperatures. Of these methods, recombinase polymerase amplification (RPA) is one of the
fastest developing, experiencing rapid uptake and market, even though it was introduced comparatively
late. Critically, RPA’s technology potentiates highly accessible and sensitive nucleic acid amplification
outside of laboratory, and even self-testing. Here we provide a comprehensive review of the equipmentfree
simplicity of RPA over its first decade of development. Our review includes key knowledge of RPA
technology, such as its reaction components, mechanism, sensitivities and specificities, and distinctive
detection methods. The review also provides know-how for developing RPA assays, and information
about commercially available RPA reaction kits and accessories. We summarise critical RPA experimental
tips and issues available through data mining the published literature, to assist researchers in mastering
the RPA reaction. We also outline influential hotspots of RPA development, and conclude with outlooks
for future development and implications for eclipsing PCR and further revolutionising the life sciences. back to the year overview K. Mitsakakis, S. Hin, P. Müller, N. Wipf, E. Thomsen, M. Coleman, R. Zengerle, J. Vontas, K. MavridisConverging Human and Malaria Vector Diagnostics with Data Management towards an Integrated Holistic One Health Approach 2018 International Journal of Environmental Research and Public Health , volume : 15, issue : 2, page : E259» show abstract « hide abstract Abstract Monitoring malaria prevalence in humans, as well as vector populations, for the presence
of Plasmodium, is an integral component of effective malaria control, and eventually, elimination.
In the field of human diagnostics, a major challenge is the ability to define, precisely, the causative
agent of fever, thereby differentiating among several candidate (also non-malaria) febrile diseases.
This requires genetic-based pathogen identification and multiplexed analysis, which, in combination,
are hardly provided by the current gold standard diagnostic tools. In the field of vectors, an
essential component of control programs is the detection of Plasmodium species within its mosquito
vectors, particularly in the salivary glands, where the infective sporozoites reside. In addition, the
identification of species composition and insecticide resistance alleles within vector populations is a
primary task in routine monitoring activities, aiming to support control efforts. In this context, the
use of converging diagnostics is highly desirable for providing comprehensive information, including
differential fever diagnosis in humans, and mosquito species composition, infection status, and
resistance to insecticides of vectors. Nevertheless, the two fields of human diagnostics and vector
control are rarely combined, both at the diagnostic and at the data management end, resulting in
fragmented data and mis- or non-communication between various stakeholders. To this direction,
molecular technologies, their integration in automated platforms, and the co-assessment of data
from multiple diagnostic sources through information and communication technologies are possible
pathways towards a unified human vector approach. K. Mitsakakis / V. D’Acremont, S. Hin, F. von Stetten, R. ZengerleDiagnostic tools for tackling febrile illness and enhancing patient management 2018 Microelectron Eng , volume : 201, pages : 26 - 59» show abstract « hide abstract Abstract Most patients with acute infectious diseases develop fever, which is frequently a reason to visit health facilities in resource-limited settings. The symptomatic overlap between febrile diseases impedes their diagnosis on clinical grounds. Therefore, the World Health Organization promotes an integrated management of febrile illness. Along this line, we present an overview of endemic and epidemic etiologies of fever and state-of-the-art diagnostic tools used in the field. It becomes evident that there is an urgent need for the development of novel technologies to fulfill end-users’ requirements. This need can be met with Point-of-Care and near-patient diagnostic platforms, as well as e-Health clinical algorithms, which co-assess test results with key clinical elements and biosensors, assisting clinicians in patient triage and management, thus enhancing disease surveillance and outbreak alerts. This review gives an overview of diagnostic technologies featuring a platform based approach: (i) assay (nucleic acid amplification technologies are examined); (ii) cartridge (microfluidic technologies are presented); (iii) instrument (various detection technologies are discussed); and at the end proposes a way that such technologies can be interfaced with electronic clinical decision-making algorithms towards a broad and complete diagnostic ecosystem. M. Kokko, S. Epple, J. Gescher, S. KerzenmacherEffects of wastewater constituents and operational conditions on the composition and dynamics of anodic microbial communities in bioelectrochemical systems 2018 Bioresource Technology , volume : 258, pages : 376 - 389» show abstract « hide abstract Abstract Over the last decade, there has been an ever-growing interest in bioelectrochemical systems (BES) as a sustainable technology enabling simultaneous wastewater treatment and biological production of, e.g. electricity, hydrogen, and further commodities. A key component of any BES degrading organic matter is the anode where electric current is biologically generated from the oxidation of organic compounds. The performance of BES depends on the interactions of the anodic microbial communities. To optimize the operational parameters and process design of BES a better comprehension of the microbial community dynamics and interactions at the anode is required. This paper reviews the abundance of different microorganisms in anodic biofilms and discusses their roles and possible side reactions with respect to their implications on the performance of BES utilizing wastewaters. The most important operational parameters affecting anodic microbial communities grown with wastewaters are highlighted and guidelines for controlling the composition of microbial communities are given. back to the year overview M. Klingele, C. Van Pham, A. Fischer, S. ThieleA Review on Metal-Free Doped Carbon
Materials Used asOxygen Reduction
Catalysts in Solid Electrolyte Proton
Exchange Fuel Cells 2016 Fuel Cells , volume : 5, pages : 522 - 529» show abstract « hide abstract Abstract Within the last decade, metal-free heteroatom doped carbon
nanomaterials have gained attention as effective electrocatalysts
for the oxygen reduction reaction (ORR) in many electrochemical
systems. Since then, reports have stated that the
ORR catalytic activity, onset potential, and H2O production
selectivity of these materials is similar to that of platinumbased
catalysts. These statements rely on cyclic voltammetry
(CV) and rotating disc electrode (RDE) measurements in
liquid alkaline electrolyte. However, fuel cell researchers aim
to replace the costly platinum catalysts in the more prominent
acidic solid electrolyte proton exchange fuel cell (PEFC).
In this respect, there are only a few reports of unpromising
activity, stability, and H2O production selectivity. In addition,
only few reports have been presented on the implementation
of such materials in cathode catalyst layers of actual
PEFC devices. This mini-review aims to summarize and evaluate
results of these reports. Material synthesis, cell power,
open circuit voltage, stability properties, and proposed active
sites are reviewed. To date, the highest reported PEFC power
densities with guaranteed metal-free heteroatom doped carbon
cathode catalysts have reached up to 321 mW cm–2;
which although a promising value is substantially short of
values obtained for platinum based catalysts. M. Karle, S. K. Vashist, R. Zengerle, F. von StettenMicrofluidic solutions enabling continuous processing and
monitoring of biological samples: A Review 2016 Anal Chim Acta , volume : 929, pages : 1 - 22» show abstract « hide abstract Abstract The last decade has witnessed tremendous advances in employing microfluidic solutions enabling Continuous Processing and Monitoring of Biological Samples (CPMBS), which is an essential requirement for the control of bio-processes. The microfluidic systems are superior to the traditional inline sensors due to their ability to implement complex analytical procedures, such as multi-step sample preparation, and enabling the online measurement of parameters. This manuscript provides a backgound review of microfluidic approaches employing laminar flow, hydrodynamic separation, acoustophoresis, electrophoresis, dielectrophoresis, magnetophoresis and segmented flow for the continuous processing and monitoring of biological samples. The principles, advantages and limitations of each microfluidic approach are described along with its potential applications. The challenges in the field and the future directions are also provided. back to the year overview O. Strohmeier, M. Keller, F. Schwemmer, S. Zehnle, D. Mark, F. von Stetten, R. Zengerle, N. PaustCentrifugal microfluidic platforms: advanced unit operations and applications 2015 Chem Soc Rev , volume : 44, pages : 6187 - 6229» show abstract « hide abstract Abstract Centrifugal microfluidics has evolved into a mature technology. Several major diagnostic companies either have products on the market or are currently evaluating centrifugal microfluidics for product development. The fields of application are widespread and include clinical chemistry, immunodiagnostics and protein analysis, cell handling, molecular diagnostics, as well as food, water, and soil analysis. Nevertheless, new fluidic functions and applications that expand the possibilities of centrifugal microfluidics are being introduced at a high pace. In this review, we first present an up-to-date comprehensive overview of centrifugal microfluidic unit operations. Then, we introduce the term “process chain” to review how these unit operations can be combined for the automation of laboratory workflows. Such aggregation of basic functionalities enables efficient fluidic design at a higher level of integration. Furthermore, we analyze how novel, ground-breaking unit operations may foster the integration of more complex applications. Among these are the storage of pneumatic energy to realize complex switching sequences or to pump liquids radially inward, as well as the complete pre-storage and release of reagents. In this context, centrifugal microfluidics provides major advantages over other microfluidic actuation principles: the pulse-free inertial liquid propulsion provided by centrifugal microfluidics allows for closed fluidic systems that are free of any interfaces to external pumps. Processed volumes are easily scalable from nanoliters to milliliters. Volume forces can be adjusted by rotation and thus, even for very small volumes, surface forces may easily be overcome in the centrifugal gravity field which enables the efficient separation of nanoliter volumes from channels, chambers or sensor matrixes as well as the removal of any disturbing bubbles. In summary, centrifugal microfluidics takes advantage of a comprehensive set of fluidic unit operations such as liquid transport, metering, mixing and valving. The available unit operations cover the entire range of automated liquid handling requirements and enable efficient miniaturization, parallelization, and integration of assays. A. Gross, J. Schoendube, S. Zimmermann, M. Steeb, R. Zengerle, P. KoltayTechnologies for Single-Cell Isolation 2015 Int J Mol Sci , volume : 16, pages : 16897 - 16919» show abstract « hide abstract Abstract The handling of single cells is of great importance in applications such as cell line
development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods.
This review provides an overview of technologies that are currently used or in development
to isolate single cells for subsequent single-cell analysis. Data from a dedicated online
market survey conducted to identify the most relevant technologies, presented here for
the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow
cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random
seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most
frequently used technologies. These most prominent technologies are described in detail and key
performance factors are discussed. The survey data indicates a further increasing interest in
single-cell isolation tools for the coming years. Additionally, a worldwide patent search was
performed to screen for emerging technologies that might become relevant in the future.
In total 179 patents were found, out of which 25 were evaluated by screening the title and
abstract to be relevant to the field. back to the year overview S. K. Vashist, E. Lam, S. Hrapovic, K. B. Male, J. H. T. LuongImmobilization of Antibodies and Enzymes on 3-Aminopropyltriethoxysilane-Functionalized Bioanalytical Platforms for Biosensors and Diagnostics 2014 Chem Rev , volume : 114, pages : 11083 - 11130» show abstract « hide abstract Abstract 1. INTRODUCTION
Biosensing and diagnostic platforms with high sensitivity,
specificity, and fast response time are based on immobilized
biomolecules such as antibodies (Abs), aptamers, enzymes,
nucleic acids, receptors, and whole cells for the detection of
target analytes. Such sensing biomolecules should be bound to
the surface of a signal transducer with a required specific
chemical, electrical, or optical property. The biological
recognition event generates a quantifiable signal, which is
equated to the amount or concentration of the analyte. Thus, the
biomolecule immobilization plays a crucial role in achieving high
sensitivity and selectivity with prolonged device lifetime. The
substrate materials such as electrodes, microtiter plates (MTPs),
nanoparticles (NPs), nanotubes, graphene, etc., for biomolecule
immobilization must be modified to introduce functional groups
that bind to biomolecules with high bonding strength, high
activity, good orientation, and excellent long-term stability.... back to the year overview B. Faltin, R. Zengerle, F. von StettenCurrent Methods for Fluorescence-Based Universal
Sequence-Dependent Detection of Nucleic Acids in
Homogenous Assays and Clinical Applications 2013 Clin Chem , volume : 59, issue : 11, pages : 1567 - 1582» show abstract « hide abstract Abstract Specific and sensitive nucleic acid (NA)
testing in research and clinical diagnostics is usually
performed by use of labeled oligonucleotide probes.
However, the use of target-specific fluorogenic probes
increases the cost of analysis. Therefore, universal
sequence-dependent (USD) NA detection methods
have been developed to facilitate cost-effective target
detection using standardized reagents. back to the year overview A. Kloke, F. von Stetten, R. Zengerle, S. KerzenmacherStrategies for the Fabrication of Porous Platinum Electrodes 2011 Adv Mater , volume : 23, pages : 4976 - 5008» show abstract « hide abstract Abstract Porous platinum is of high technological importance due to its various
applications in fuel cells, sensors, stimulation electrodes, mechanical actuators
and catalysis in general. Based on a discussion of the general principles
behind the reduction of platinum salts and corresponding deposition
processes this article discusses techniques available for platinum electrode
fabrication. The numerous, different strategies available to fabricate platinum
electrodes are reviewed and discussed in the context of their tuning
parameters, strengths and weaknesses. These strategies comprise bottomup
approaches as well as top-down approaches. In bottom-up approaches
nanoparticles are synthesized in a fi rst step by chemical, photochemical or
sonochemical means followed by an electrode formation step by e.g. thin fi lm
technology or network formation to create a contiguous and conducting solid
electrode structure. In top-down approaches fabrication starts with an already
conductive electrode substrate. Corresponding strategies enable the fabrication
of substrate-based electrodes by e.g. electrodeposition or the fabrication
of self-supporting electrodes by dealloying. As a further top-down strategy,
this review describes methods to decorate porous metals other than platinum
with a surface layer of platinum. This way, fabrication methods not performable
with platinum can be applied to the fabrication of platinum electrodes
with the special benefi t of low platinum consumption. back to the year overview M. Focke, D. Kosse, C. Müller, H. Reinecke, R. Zengerle, F. von StettenLab-on-a-Foil: microfluidics on thin and flexible films 2010 Lab Chip , volume : 10, pages : 1365 - 1386» show abstract « hide abstract Abstract For the first time we demonstrate a self-sufficient lab-on-a-foil system for the fully automated analysis
of nucleic acids which is based on the recently available isothermal recombinase polymerase
amplification (RPA). The system consists of a novel, foil-based centrifugal microfluidic cartridge
including prestored liquid and dry reagents, and a commercially available centrifugal analyzer for
incubation at 37°C and real-time fluorescence detection. The system was characterized with an assay
for the detection of the antibiotic resistance gene mecA of Staphylococcus aureus. The limit of detection
was <10 copies and time-to-result was <20 min. Microfluidic unit operations comprise storage and
release of liquid reagents, reconstitution of lyophilized reagents, aliquoting the sample into #30
independent reaction cavities, and mixing of reagents with the DNA samples. The foil-based cartridge
was produced by blow-molding and sealed with a self-adhesive tape. The demonstrated system excels
existing PCR based lab-on-a-chip platforms in terms of energy efficiency and time-to-result.
Applications are suggested in the field of mobile point-of-care analysis, B-detection, or in combination
with continuous monitoring systems. D. Mark, S. Häberle, G. Roth, F. von Stetten, R. ZengerleMicrofluidic lab-on-a-chip platforms: requirements, characteristics and applications 2010 Chem Soc Rev , volume : 39, pages : 1153 - 1182» show abstract « hide abstract Abstract This critical review summarizes developments in microfluidic platforms that enable the miniaturization, integration,automation and parallelization of (bio-)chemical assays (see S. Haeberle and R. Zengerle, Lab Chip, 2007, 7, 1094–1110, for an earlier review). In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology.
This allows the easy, fast, and cost-efficient implementation of different application-specific (bio-)chemical processes.
In our review we focus on recent developments from the last decade (2000s). We start with a brief introduction into
technical advances, major market segments and promising applications. We continue with a detailed characterization
of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations,application examples as well as strengths and limitations of every platform. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electrokinetics, electrowetting, surface acoustic waves, and dedicated systems for massively parallel analysis. This review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposability, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols (295 references). back to the year overview S. Kerzenmacher, J. Ducrée, R. Zengerle, F. von StettenEnergy Harvesting by Implantable Abiotically Catalyzed Glucose Fuel Cells 2008 J Power Sources , volume : 182, issue : 1, pages : 1 - 17» show abstract « hide abstract Abstract Abiotically catalyzed glucose fuel cells are a newly re-discovered approach to realize an autonomous energy supply for low power medical implants that solely relies on the electrochemical reaction of oxygen and glucose available from body fluids. The key advantage of a fuel cell driven power supply over conventional battery based approaches is the abundant availability of both reactants in body fluids, rendering the need for regular battery replacement or external charging mechanisms obsolete. Abiotic electrode catalysts, such as noble metals or activated carbon, exhibit favorable characteristics for long-term application in an implantable glucose fuel cell. In contrast to enzymes they are long-term stable and amenable to heat sterilization and corresponding fuel cells have already been developed in the late 1960s. However, the concept has drawn only little attention over the last decades, and research has mainly been focused on the development of enzymatic glucose fuel cells. This review therefore covers the development of implantable glucose fuel cells based on abiotic catalysts since the 1960s, with special regard to their applicability as sustainable micro power generators for implantable devices. The historical achievements of various academic and industrial research groups are critically reviewed, and different embodiment concepts are presented. While encouraging results have been achieved both in in-vitro and in preliminary in-vivo experiments, no further developments have been reported since the introduction of implantable lithium iodine batteries in the mid 1970s. In terms of design and fabrication of operational devices only limited information is documented in the literature, and further effort will be necessary to develop an understanding of the parameters influencing device performance and stability under in-vivo conditions. back to the year overview Ducree,J., Haeberle,S., Lutz,S., Pausch,S., von Stetten,F., Zengerle,R.The centrifugal microfluidic Bio-Disk platform 2007 Journal of Micromechanics and Microengineering , volume : 17, pages : S103 - S115
Books Years: 2004 |
1994 | show all back to the top of all publications back to the year overview Books on Demand GmbH, Norderstedt, Germany , page : 197FlowMap - Microfluidics Roadmap for the Life Sciences ISBN : 3-8334-0744-1 Ducrée J, Zengerle R» show abstract « hide abstract Abstract The report is based on a 15-month European project "FlowMap - Microfluidics Roadmap for the Life Sciences" lead by the Institute of Microsystem Technology (IMTEK). In the course of the project, present and emerging markets for microfluidic technologies in the life sciences have been investigated. Important market demands, major technology drivers and strategic issues are identified and analyzed in a global market research chapter as well as individual discovery, medicine and ecology. The present markets and expected growth rates are quantified to forecast the evolution of the market volume. A 19% annual growth rate starting from a 2002-turnover of 500 M and reaching 1.4 billion in 2008 is estimated. The results are based on personal interviews and a questionnaire action involving more than 150 key experts in the life-science fields, representing end users, system suppliers and developers of unterlying microfluidic technologies. In addition, the report features an introduction into microfluidic technologies. back to the year overview Shaker Mikro-Membranpumpen als Komponenten für Mikro-Fluidsysteme (Dissertation) ISBN : 3-8265-0216-7 Zengerle R
Book chapters Years: 2020 |
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2003 | show all back to the top of all publications back to the year overview A. Brunauer, H. Ceren Ates, C. Dincer, S. M. FrühIntegrated paper-based sensing devices for diagnostic applications In : Comprehensive Analytical Chemistry 2020, Elsevier , » show abstract « hide abstract Abstract Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices. back to the year overview J. Riba, S. Zimmermann, P. KoltayTechnologies for Automated Single Cell
Isolation In : Handbook of Single Cell Technologies 2018, Springer Nature , T. S. Santra, F.-G. Tseng, T. S. Santra, F.-G. Tseng, ISBN : 978-981-10-4857-9» show abstract « hide abstract Abstract The isolation of individual cells has gained tremendous importance with the
advent of new methods for highly parallel single-cell analysis. A prerequisite
for effective clonal cultivation or single-cell analysis is the efficient isolation of
individual cells from liquid cell suspensions. This review provides an overview of
technologies that are used to automate the isolation of single cells for subsequent
cultivation or analysis. First, currently available technologies are classified based
on their major technical characteristics. Then, the most prominent technologies such as limiting dilution, FACS, single-cell printing, hydrodynamic trapping,
droplet microfluidics, and cell manipulation by external forces are described
in detail. Furthermore, the individual features of each technology with focus
on throughput, isolation efficiency, level of automation, flexibility in terms of
cell types, and their suitability for specific downstream processing and analysis
methods are discussed. In contrast to previous works, this review provides
a classification approach for single-cell isolation technologies according to performance
requirements, makes specific reference to methods for the isolation of
microbial cells, and discusses sample input requirements, which is an important
aspect in particular for diagnostic purposes. back to the year overview A.G. Venkatesh, T. van Oordt, E. M. Schneider, R. Zengerle, F. von Stetten, J.H.T. Luong, S.K. VashistA Smartphone-Based Colorimetric Reader for Human
C-Reactive Protein Immunoassay In : Biosensors and Biodetection: Methods and Protocols Volume 1:
Optical-Based Detectors, Methods in Molecular Biology, vol. 1571 2017, Springer , Avraham Rasooly and Ben Prickril, pages : 343 - 356, Avraham Rasooly and Ben Prickril, » show abstract « hide abstract Abstract A smartphone-based colorimetric reader (SBCR), comprising a Samsung Galaxy SIII mini, a gadget (iPAD
mini, iPAD4, or iPhone 5s) and a custom-made dark hood and base holder assembly, is used for human Creactive
protein (CRP) immunoassay. A 96-well microtiter plate (MTP) is positioned on the gadget’s
screensaver to provide white light-based bottom illumination only in the specific regions corresponding to
the well’s bottom. The images captured by the smartphone’s back camera are analyzed by a novel image
processing algorithm. Based on one-step kinetics-based human C-reactive protein immunoassay (IA), SBCR
is evaluated and compared with a commercial MTP reader (MTPR). For analysis of CRP spiked in diluted
human whole blood and plasma as well as CRP in clinical plasma samples, SBCR exhibits the same precision,
dynamic range, detection limit, and sensitivity as MTPR for the developed IA (DIA). Considering its
compactness, low cost, advanced features and a remarkable computing power, SBCR is an ideal point-ofcare
(POC) colorimetric detection device for the next-generation of cost-effective POC testing (POCT). back to the year overview S. K. Vashist, A.G. Venkatesh, R. Zengerle, F. von Stetten, J.H.T. LuongSmartphone-based in vitro diagnostic technologies for personalized healthcare monitoring and management In : Nanobiosensors for personalized and onsite biomedical diagnosis 2016, The Institution of Engineering and Technology, UK , Pranjal Chandra, pages : 231 - 251, Pranjal Chandra, ISBN : 978-1-84919-950-6 back to the year overview M. Blazek, G. Roth, R. Zengerle, M. MeierMicrofluidic Proximity Ligation Assay for Profiling Signaling Networks with Single-Cell Resolution In : Springer Protocol: Single Cell Protein Analysis 2015, Springer , Anup K. Singh, Aarthi Chandrasekaran, pages : 169 - 184, Anup K. Singh, Aarthi Chandrasekaran, » show abstract « hide abstract Abstract The proximity ligation assay (PLA) is a technique that can be used to characterize proteins, protein–protein interactions, and protein modifications at the single-cell level. Image-based in situ detection of proteins using PLA is a quantitative method with a high degree of sensitivity and specificity. The miniaturization and parallelization of the PLA onto a microfluidic chip and concurrent use of an automated cell-culture system increase the throughput of this technology. Here, we describe the performance of PLA on a microfluidic chip. We provide protocols for on-chip cell culture, time-shifted cell stimulation and fixation, PLA implementation, and computational image analysis in order to achieve single-cell resolution. As a proof of concept, we studied the phosphorylation of Akt in response to stimulation with platelet-derived growth factor. S.K. Vashist, A.G. Venkatesh, R. Zengerle, F. von Stetten, J.H.T. LuongSmart-phone based Point-of-Care for mobile healthcare In : Handbook of Biotechnology, Bioengineering and Biomedical Applications 2015, National Design and Research Forum , Gundu H. R. Rao and Dr. L.V. Muralikrishna Reddy, pages : 313 - 332, Gundu H. R. Rao and Dr. L.V. Muralikrishna Reddy, back to the year overview D. Mark, F. von Stetten, R. ZengerleLab on a Chip: The Vision Becomes Reality In : Smart Systems Integration for Micro- and Nanotechnologies 2014, goldenbogen , pages : 73 - 81, ISBN : 9783932434785» show abstract « hide abstract Abstract This chapter elucidates the current socio-economical status of Lab-on-a-Chip (LOAC) technology. It starts from the original vision of LOAC to miniaturize and automate assays by microfluidic integration and then focusses on microfluidic Lab-on-a-Chip products in the field of point-of-care (POC)diagnostics. These are discussed in the light of their market impact, approval by the FDA (Food and Drug Administration), and their status of process integration and automation as categorized by the CLIA (Clinical Laboratory Improvement Amendments). Future requirements to strenghten the competiveness of microfluidic based POC products are seen in the implementation of a microfluidic platform based development approach, and foundry based manufacturing process. S. Wadle, S. Rubenwolf, M. Lehnert, B. Faltin, M. Weidmann, F. Hufert, R. Zengerle, F. von StettenMediator Probe PCR: Detection of Real-Time PCR
by Label-Free Probes and a Universal Fluorogenic Reporter In : Quantitative Real-Time PCR: Methods and Protocols 2014, Springer , R. Biassoni, A. Raso, HUMANA PRESS INC., pages : 55 - 73, R. Biassoni, A. Raso, HUMANA PRESS INC., » show abstract « hide abstract Abstract Mediator probe PCR (MP PCR) is a novel detection format for real-time nucleic acid analysis. Label-free mediator probes (MP) and fluorogenic universal reporter (UR) oligonucleotides are combined to accomplish signal generation. Compared to conventional hydrolysis probe PCRs costs can thus be saved by using the same fluorogenic UR for signal generation in different assays. This tutorial provides a practical guideline to MP and UR design. MP design rules are very similar to those of hydrolysis probes. The major difference is in the replacement of the fluorophore and quencher by one UR-specific sequence tag, the mediator. Further protocols for the setup of reactions, to detect either DNA or RNA targets with clinical diagnostic target detection as models, are explained. Ready to use designs for URs are suggested and guidelines for their de novo design are provided as well, including a protocol for UR signal generation characterization. back to the year overview S. Haeberle, D. Mark, F. von Stetten, R. ZengerleMicrofluidic Platforms for Lab-on-a-Chip Applications In : Microsystems and Nanotechnology 2012, Springer , Z. Zhou, Z. Wang, L. Lin, pages : 853 - 895, Z. Zhou, Z. Wang, L. Lin, ISBN : 978-3-642-18293-8 back to the year overview Mark D, Haeberle S, Roth G, Stetten von F, Zengerle RMicrofluidic Lab-on-a-Chip Platforms: Requirements, Characteristics and Applications In : Microfluidic Based Microsystems: Fundamentals and Applications 2010, Springer Verlag , S. Kakac, B. Kosoy, D. Li, A. Pramuanjaroenkij, pages : 305 - 376, S. Kakac, B. Kosoy, D. Li, A. Pramuanjaroenkij, ISBN : 978-90-481-9031-7» show abstract « hide abstract Abstract This review summarizes recent developments in microfluidic platform approaches. In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the implementation of different application-specific (bio-)chemical processes, automated by microfluidic process integration [1]. A brief introduction into technical advances, major market segments and promising applications is followed by a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electrokinetics, electrowetting, surface acoustic waves, and systems for massively parallel analysis. The review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposable, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols. back to the year overview Shoji,S., Sato,H., Zengerle,R.Liquid Micropumps In : Comprehensive Microsystems – Fundamentals, technology and applications 2007, Elsevier , Y. Gianchandani, O. Tabata, H. Zappe, pages : 301 - 322, Y. Gianchandani, O. Tabata, H. Zappe, ISBN : 0-444-52194-1 Zengerle,R., Ducree,J.The Future of Microfluidics: Low-Cost Technologies and Microfluidic Platforms In : Microsystems and Nanotechnology 2007, Springer , pages : 806 - 813, back to the year overview Koltay P, Ducrée J, Zengerle RMicrofluidic Platforms In : BioMEMS 2006, Springer Verlag , Gerald A. Urban, pages : 139 - 165, Gerald A. Urban, ISBN : 10 0-387-28731-0 Ducrée J, Koltay P, Zengerle RMicrofluidics In : MEMS: A Practical Guide to Design, Analysis, and Applications 2006, William Andrew Publishing , Jan G. Korvink, Oliver Paul, pages : 667 - 727, Jan G. Korvink, Oliver Paul, ISBN : 0-8155-1497-2 Zengerle RMikrosystemtechnik und Nanotechnologie: Technologien im Kleinen mit enormen Impact In : Festschrift 10 Jahre GMM 2006, GMM Frankfurt , page : 87ff, back to the year overview Koltay P, Ducrée J, Zengerle RNanoliter and Picoliter Liquid Handling In : Lab-On-A-Chip: Miniaurized Systems for (Bio) Chemical Analysis and Synthesis 2003, Elsevier Science , Edwin Oosterbroek, Albert van den Berg, pages : 151 - 171, Edwin Oosterbroek, Albert van den Berg, ISBN : 0-444-51100-8
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1993 | show all back to the top of all publications back to the year overview J. Schemberg, M. Specht, M. KarleNeue Wege in der Krebsdiagnostik - Mikrofluidische Strategien für die Medizin 4.0 2018 GIT-Laborfachzeitschrift , volume : 4, page : 16 back to the year overview N. Borst, F. von StettenEine Technologieplattform für die digitale Nukleinsäureanalytik 2017 Management & Krankenhaus , volume : 2017-04, page : 37 J. Riba, S. Zimmermann, B. Steimle, A. GrossVereinzelung von prokaryotischen und eukaryotischen Zellen 2017 BIOspektrum , volume : 23, pages : 298 - 300 back to the year overview J. MerzGroße Hoffnung in kleinen Tröpfchen 2016 Laborjournal , volume : 11 back to the year overview F. Schuler, F. von StettenTröpfchenschleuder 2015 Laborjournal , volume : 7-8, pages : 52 - 53
Download file back to the year overview B. Faltin, S. Wadle, G. Roth, S. Rubenwolf, M. Lehnert, R. Zengerle, F. von StettenNeuer Echtzeit-Nachweis von Nukleinsäuren 2012 Laborwelt , volume : 4, pages : 10 - 11 back to the year overview Daniel Mark, Günter Roth, Dominique Kosse, Nils Paust, Roland Zengerle, Felix von StettenAssay-Automatisierung als Dienstleistung - Mikrofluidische Integration von Laborprozessen durch den Lab-on-a-Chip Design- & Foundry-Service 2011 Labo , volume : April, pages : 10 - 13 D. Mark, G. Roth, R. Zengerle, F. von StettenLaborautomation - Die zentrifugal-mikrofluidische Plattform 2011 BIOspektrum , issue : 6, pages : 1 - 4 S. Spieth, S. MessnerMikrodosiersysteme machen funktionellere Lösungen möglich 2011 MaschinenMarkt , volume : 42, pages : 26 - 29 back to the year overview Andreas Ernst, Peter KoltayAuch Mikrotropfen besitzen "Fingerabdrücke" 2008 A&D Kompendium , pages : 191 - 194 back to the year overview Woias P, Manoli Y, Nann T, von Stetten FEnergy Harvesting for Autonomous Microsystems 2005 mst-news , volume : 4, pages : 42 - 45 back to the year overview Jens Ducrée, Bas de Heij, Hermann Sandmaier, Roland Zengerle; Fabrication of microarrays on an industrial, scale with TopSpot; mstnews; No 4/2000; September 2000Fabrication of microarrays on an industrial scale with TopSpot 2000 mstnews; No 4/2000 (Sept. 2000) , pages : 22 - 23 back to the year overview Zengerle R, Richter AMikropumpen als Komponenten für Mikrosysteme 1993 Physik in unserer Zeit , volume : 24, issue : 2, pages : 86 - 90
Talks Years: 2024 |
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1999 | show all back to the top of all publications back to the year overview E. Kipf, P. Jülg, F. Schlenker, M. Fillies, C. Kranig, M. Specht, S. Groeneveld-Krentz, S. Neumann, R. Zengerle, F. von Stetten, N. Borst, R. Kirschner-Schwabe, T. Hutzenlaub, M. Lehnert, C. EckertMessung des individuellen Therapieansprechens von akuten lymphoblastischen Leukämien (IRMA-4-ALL) 2024 Translationale Forschung in der Personalisierten Medizin – Chancen und Hürden, Netzwerkveranstaltung für geförderte Projekte der „Innovationen für die individualisierte Medizin“ und der „Translationsp back to the year overview K. Seteiz, J. Häberlein, J. Disch, L. Bohn, P. Heizmann, S. VierrathCarbon black supported Ag NPs for CO2 reduction to CO 2023 29. Internes FMF-Kolloquium am FIT, Titisee, 10.10.2023 L. BohnIntegrated reference electrodes for CO2 electrolysis cells 2023 29. Internes FMF-Kolloquium am FIT, Titisee, 10.10.2023 back to the year overview M. Elshamy, L. Metzler, S. VierrathAssessing the electronic and ionic conductivity of NiFe-LDH-based catalyst layers for AEMWEs 2022 Workshop on Ion Exchange Membranes for Energy Applications, Bad Zwischenahn, June 20 – 22, 2022 L. Metzler, S. Koch, M. Elshamy, S. Kilian, M. Breitwieser, S. VierrathFully casted catalyst coated membranes for anion exchange membrane water electrolysis 2022 Workshop on Ion Exchange Membranes for Energy Applications, Bad Zwischenahn, June 20 – 22, 2022 J. Häberlein, K. Seteiz, P. Heizmann, J. Disch, S. VierrathLow loaded carbon supported Ag nanoparticles for CO2 to CO electrolysis showing high mass activities 2022 Symposium Nano-BW 2022 des Kompetenznetzes „Funktionelle Nanostrukturen“, Bad Herrenalb, December, 6-7, 2022 F. Pescher, M. von HolstParticle Atomic Layer Deposited Overcoatings for Improving the Durability of Proton Exchange Membrane Fuel Cells 2022 Symposium Nano-BW 2022 des Kompetenznetzes „Funktionelle Nanostrukturen“, Bad Herrenalb, December, 6-7, 2022 M. von Holst, L. Pavko, J. Stiegeler, P. A. Heizmann, A. Salihi, M. Gatalo, N. Hodnik, C. Klose, S. Vierrath, M. BreitwieserReduced graphene oxide as durable carbon support for PtCo catalyst in proton exchange membrane fuel cells 2022 Symposium Nano-BW 2022 des Kompetenznetzes „Funktionelle Nanostrukturen“, Bad Herrenalb, December, 6-7, 2022 back to the year overview K. MitsakakisConverging Human, Animal, and Vector Diagnostics, together with Digital Technologies, towards a Holistic One Health Approach 2019 Molecular Diagnostics Europe, Lissabon/Portugal, 06. - 09.05.2019 back to the year overview S. Vierrath, M. Breitwieser, C. Klose, M. Klingele, S. ThieleNovel approaches to tailor the PEM|electrode interface for fuel cells with increased power density 2018 innBW Wissenschaftlertreffen Stuttgart, 21.04.2018 M. Breitwieser, S. VierrathNeue Kompositmembranen und Mikrocharakterisierung: Die Gruppe „Elektrochemische Energiesysteme“ an IMTEK und Hahn-Schickard 2018 Brennstoffzellenallianz Duisburg, 26. - 27. Juni 2018 L. BechererTherapiebegleitende HIV- und HTLV-Diagnostik am Point-of-Care 2018 microTEC Südwest Clusterkonferenz 2018, 16. – 17.04.2018, Freiburg back to the year overview F. Schuler, S. Wadle, N. Borst, M. Schulz, L. Becherer, J. Li, M. Specht, T. Hutzenlaub, N. Paust, R. Zengerle, F. von StettenA Technology Platform for Digital Nucleic Acid Diagnostics at the Point of Care (invited talk) 2017 3. Münchner point-of-care testing symposium, Deutsche Gesellschaft für Klinische Chemie und Laboratoriumsmedizin (DGKL), München, 13.-15. 3. 2017 F. von StettenA technology platform for digital nucleic acid testing at the point of need (invited talk) 2017 Potsdam Days on Bioanalysis 2017, Potsdam, 23.-24.11.2017 F. Schuler, N. Borst, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, T. Hutzenlaub, N. Paust, R. Zengerle, F. von StettenCentrifugal Step Emulsification Allows Miniaturized Digital Droplet-RPA,-LAMP and -PCR on the Centrifugal Microfluidic Platform (invited talk) 2017 9th Annual lab-on-a-chip & microfluidics Conference, Selectbio, Munich, 10.-11.5. 2017 P. Kocatürk Schumacher, J. Madjarov, P. Viwatthanasittiphong, S. KerzenmacherIncreasing the energy efficiency of an AnMBR by using the membrane as microbial anode 2017 5. Workshop der Plattforminitiative Mikrobielle Bioelektrotechnologie, Rüsselsheim, 29.11.2017 back to the year overview F. von StettenAccelerated Development of Multiplex Real-Time PCR by Preloaded Fluorogenic Reporters and Label-Free Mediator Probes (talk) 2016 4th Point-of-Care Diagnostics & Global Health World Congress 2016, San Diego USA, 26.-28.09.2016 F. von StettenAccelerated development of multiplex real-time PCR by a fluorogenic mastermix (invited talk) 2016 4th qPCR and Digital PCR Congress, London / UK 20.-21.10.2016 F. von StettenCentrifugal Step Emulsification Allows Miniaturized Digital Droplet-RPA, -LAMP and -PCR on the Centrifugal Microfluidic Platform (talk) 2016 8th Lab-on-a-Chip, Microfluidics & Microarrays World Congress 2016, San Diego USA, 26.-28.09.2016 C. Klose, M. Breitwieser, L. Zielke, S. Vierrath, H. Cho, S. Thiele, J. Kerres, R. ZengerleLong-life and high-power PEMFCs by combination of direct electrospinning and inkjet printing, 2016 Statusworkshop der Baden-Württemberg Stiftung, Bad Herrenalb, 2016 S. Thiele, S. Vierrath, R. Moroni, L. Zielke, R. ZengerleMultiple scales and interfaces in PEMFCs - a tomographic study 2016 Electrocatalysis Workshop, Vancouver, February 2016. F. von StettenNeue Ansätze zur nukleinsäurebasierten Vor-Ort-Diagnostik von Infektionskrankheiten (invited talk) 2016 Fachtagung Bio Medizin Technik: Innovationen in Diagnostik und Therapie von Infektionen, Hannover, 06.4.2016 M. Breitwieser, M. Klingele, B. Britton, S. Vierrath, R. Zengerle, S. Holdcroft, S. ThieleRecent Progress in Low- and No- Pt loaded PEMFCs 2016 Electrocatalysis Workshop, Vancouver, February 2016 S. Vierrath, L. Zielke, R. Moroni, A. Mondon, R. Zengerle, S. ThieleZnO Contrasted Nano Tomographies of Fuel Cell and Battery Components 2016 MODVAL 13, Symposium for Fuel Cell and Battery Modeling and Experimental Validation, Lausanne, Schweiz (22.-23.03.2016) back to the year overview F. von StettenMediator probe PCR – label free probes and universal fluorogenic reporters for the detection of different RNA and DNA sequences (talk) 2015 Spring meeting, European Materials Research Society, Lille, France, 11.-15.05.2015 S. Vierrath, F. Güder, A. Menzel, M. Hagner, R. Zengerle, M. Zacharias, S. ThieleNovel Approach in 3D-Reconstructions of PEMFC Catalyst Layers: Infiltration aided Segmentation
2015 ModVal 12, Munzingen, Deutschland, 26.-27. März 2015 L. Zielke, S. Vierrath, R. Moroni, R. Zengerle, S. ThieleTransport, Degradation and Multi-Scale Morphology in X-ray Tomographic Reconstructions of Battery Electrodes 2015 Solid State Electrochemical Workshop 2015, Roggenburg, Germany, 06. – 09.09.2015 J. Eipper, A. Barske, K. Sturm-Richter, J. Gescher, S. KerzenmacherUsing an enzyme secreting, genetically modified E. coli strain to supply Bilirubin Oxidase to a biofuel cell cathode 2015 Annual Conference 2015 of the Association for General and Applied Microbiology (VAAM) in Marburg, 01. - 04.03.2015 back to the year overview N. Lass, L. Riegger, R. Zengerle, P. KoltayDirektes Drucken von metallischer Mikrostrukturen mit der StarJet Technologie 2014 Clusterkonferenz MicroTEC Südwest, Freiburg, 05.-06.05.2014 S. Kartmann, A. Ernst, R. Zengerle, P. KoltayE-DosiS: Einweg-Dosiersystem mit intelligenter Sensorik 2014 Clusterkonferenz MicroTEC Südwest, Freiburg, 05.-06.05.2014 F. von StettenLabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges (invited key-note presentation) 2014 Biosensors 2014, Melbourne, Australia, 27.-30.05.2014 F. von StettenLabTube and LabDisk - prospective centrifugal microfluidic platforms for sample-to-answer point-of-care nucleic acid testing (invited key-note presentation) 2014 Lab‐on‐a‐Chip World Congress, San Diego/USA, 18. - 19. September 2014 F. von StettenLabTube – a novel "microfluidic app" for sample preparation and diagnostics operated in a laboratory centrifuge (invited talk) 2014 Lab-on-a-Chip European Congress, SelectBio, Berlin, 10.-11.03.2014 F. von StettenMediator Probe PCR - Principle, Applications and Guidelines for Primer and Probe Design (invited talk) 2014 Advances in Biodetection & Biosensors, Berlin, 10.-11. 03.2014 S. Vierrath, F. Güder, A. Menzel, R. Zengerle, M. Zacharias, S. ThieleNovel Approach in 3D-Reconstructions of PEMFC Catalyst Layer 2014 97th Canadian Chemistry Conference and Exhibition”, Vancouver, Kanada, 01. - 05. Juni 2014 S.K. Vashist, T. van Oordt, A. Kloke, F. Von Stetten, R. ZengerleSmartphone-based colorimetric readers (SBCR) for bioanalytical applications and SBCR-based in vitro diagnostics for mobile healthcare 2014 Clusterkonferenz MicroTEC Südwest, Freiburg, 05.-06.05.2014 F. von StettenUniversal reporters of mediator probe PCR as target-independent biosensors for detection of five different RNA and DNA sequences (invited key-note presentation) 2014 Biosensors 2014, Melbourne, Australia, 27.-30.05.2014 back to the year overview Lehnert M, Wadle S, Stetten F, Zengerle RMediator probe PCR as tool for personalized medicine 2013 BmbF R. Zengerle, D. Mark, O. Strohmeier, D. Kosse, N. Paust, F. von Stetten, G. Czilwik, T. van Oordt, M. Keller, J. DrexlerLabDisk - a set of novel centrifugal microfluidc unit operations enables point of care sample-to-answer nucleic acid testing 2013 Gordon Research Conference on ”Physics and Chemistry of Microfluidics: Challenges, Advances and New Technologies for Diagnostics” in Lucca, Tuscany, Italy , 09. – 14.06.2013 F. von StettenLabDisk - a set of novel centrifugal microfluidc unit operations enables point of care sample-to-answer nucleic acid testing (talk) 2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 F. von Stetten, A. Kloke, A. Fiebach, L. Drechsel, S. Zhang, N. Paust, J. Steigert, R. ZengerleLabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges 2013 Gordon Research Conference on ”Physics and Chemistry of Microfluidics: Challenges, Advances and New Technologies for Diagnostics” in Lucca, Tuscany, Italy , 09. – 14.06.2013 F. von Stetten, B. PunnamoottilLabor im Zentrifugenröhrchen zur dezentralen patientennahen Diagnostik (invited talk) 2013 Mobile Diagnostik am Point-of-Care, Deutsche Gesellschaft für Biomedizinische Technik, Düsseldorf, 13.11.2013 F. von StettenPhysikalische und biologische Sensoren, fluidische Integration, und Fertigungstechnologie mit einem Anwendungsbeispiel zur Wasseranalytik (invited talk) 2013 Fachsymposium des Vereins HybridSensorNet, Karlsruhe, 29.11.2013 back to the year overview F. von StettenA functional blister-pack LabDisk system for point of care testing (invited talk) 2012 6th Workshop “Chemical and Biological Micro Laboratory Technology“, Ilmenau/Elgersburg, Germany, 2012 R. Zengerle, J. Hoffmann, G. Roth, D. Mark, F. von StettenMicrofluidic Apps for off-the-shelf Instruments 2012 1st International POSTECH Biomedical Device Workshop 2012; Pohang, Korea , 19.07.2012- 20.07.2012 A. Gross, J. Schoendube, W. Streule, L. Riegger, R. Zengerle, P. Koltay 1 3Non-contact, label-free printing of single, living cells 2012 IMTEK Poster Session, Okt. 2012, Freiburg back to the year overview F. von StettenA functional blister-pack LabDisk system for rapid field testing of biological threats (invited talk) 2011 18th Annual Biodetection Technologies, Washington, 23.06.2011 F. von StettenCentrifugal Microfluidic Platform for Molecular Diagnostics (talk) 2011 19th IFCC-EFCC European Congress of Clinical Chemistry and Laboratory Medicine, Berlin, 15- 19.05.2011 back to the year overview F. von Stetten, M. Focke, S. Lutz, B. Faltin, J. Burger, P. Weber, C. Mueller, T. Metz, G. Roth, D. Mark, R. ZengerleMiniaturisation, automation and integration of biochemical assays based on centrifugal microfluidics (talk) 2009 6. Deutschen BioSensor Symposiums, Freiburg, 2009 back to the year overview Zengerle RMicrofluidic Platforms for Miniaturization, Integration and Automation of Assays 2007 Proc. Transducers 2007, Lyon, France back to the year overview Zengerle RMicrofluidics: From Application Specific Microfluidic Solutions to Integrated Microfluidic Platforms 2006 Micro Mechanics Europe (MME); 3-5th Sept 2006 in Southampton, UK Zengerle RMicrofluidics: From Discrete Solutions to Integrated Microfluidic Platforms 2006 2nd International Symposium of Micro and Nano Technology (ISMNT-2); March 29-31, 2006 in Hsinchu, Taiwan back to the year overview Zengerle RBio-Disk - A Versatile Centrifugal Microfluidic Platform for Point of Care Diagnostics 2005 "Lab-on-Microchip" Symposium at University of Siegen, Germany Ducrée J, Grumann M, Brenner T, Zengerle RBio-Disk: A Flexible and Versatile Microfluidic Platform for Assay Automation 2005 Proc. BMT 2005; 39th Annual Congress of the German Society for Biomedical Engineering (DGMBT) within VDE; Nuremberg, Germany Santer M, Moseler M, Cupelli C, Henrich B, Wonisch A, Glatzel T, Zengerle RDissipative Particle Dynamics as a practical Simulation Tool for Nanofluidic Applications 2005 Proc. "First International Nanofluidics Workshop"; Boekelo, the Netherlands Niekrawietz R, Honstein W, Gutmann O, de Heij B, Zengerle R, Daub MIntegrated Process Control For Highly Parallel and Contact Free Microarray Printing 2005 Proc. "Statusseminar Chiptechnologien - Technologien und Anwendungen"; Dechema Haus, Frankfurt, Germany Kohnle J, Schumacher A, Goettsche T, Messner S, Zengerle RIntelliDrug - Intelligentes Medikamenten-Mikrodosiersystem für den Mundraum 2005 Proc. Mikrosystemtechnik-Kongress 2005, Freiburg, Germany back to the year overview Zengerle RMicrofluidics & Highly Parallel Picoliter and Nanoliter Dispensing 2004 Industrial Forum at Kyoto University, Japan back to the year overview Ducrée J, Zengerle R, Newman J, Ernst H, Riedmueller K, Messner S, Anrieux G, Provence MFlowMap - Microfluidics Roadmap for the Life Sciences 2003 8th International Conference on the Commercialization of Micro and Nano Systems 2003; Amsterdam, The Netherlands Grumann M, Dobmeier M, Schippers P, Brenner T, Zengerle R, Ducrée J, Kuhn C, Fritsche MHydrodynamic Creation of Monolayers for Parallel Readout of Bead-Based Assays 2003 NanoTec 2003; Montreux, Switzerland back to the year overview Peter KoltayA novel Fixed Volume Dispenser for the Massive Parallel
Liquid Handling of Nanoliter Volumes. (EuroLabAutomation; 23-25 October 2001; London). 2001 back to the year overview Zengerle RNanoliter Liquid Handling 1999 IBC-conference Microfabrication and Microfluidics 99, San Francisco Zengerle RNanoliter Liquid Handling 1999 IBC-conference BioChip Technologies, Edinburgh Ducrée JTopSpot 1999 Proc. Nanotechnologie, Montreux
Conference papers Years: 2024 |
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1992 | show all back to the top of all publications back to the year overview K. Seteiz, H. Grammel, J. Häberlein, P. Heizmann, L. Metzler, M. Günthel, M. Knäbbeler-Buß, S. Vierrath, J. Disch4-Aminothiophenol as anchoring agent for Ag/C catalysts in CO2 electrolysis to CO 2024 PSI Symposium, Villigen / Switzerland, 06.06.2024 T-T. Truong, Y. Kaku, J. Schlanderer, F. Schlenker, E. Kipf, E. Dazert, F. Axt, N. von Bubnoff, S. Kartmann, N. Borst, N. Paust, T. Hutzenlaub, P JuelgA robotic microfluidic approach for rapid sample-to-answer analysis of cell-free DNA 2024 13th CNAPS International Symposium on Circulating Nucleic Acids in Plasma and Serum, Graz/Austria, 4-6 March 2024 L. Hagner, L. Metzler, S. Koch, M. Klingenhof, P. Strasser, R. Weber, M. Landrock, M. Sommer, S. VierrathAEM Water Electrolysis with Ni-based Catalysts and Tailored Poly(arylene piperidinium) Materials for Improved Stability 2024 245th ECS Meeting, San Francisco, CA, 26. -30.05.2024 L. Metzler, M. El Shamy, L. Hagner, K. Seteiz, J. Disch, S. Koch, S. VierrathApplication of Anion Exchange Mambranes for AEMWE and CO2 Electrolysis 2024 EMEA 2024, Bad Zwischenahn, 16 -18 June, 2024 R. Voelckner, G. Miotto, R. Zengerle, S. KartmannCamera-based jet volume estimation using deep learning 2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024 S. Koch, J. Disch, S. K. Kilian, M. Elshamy, L. Metzler, S. VierrathCatalyst Layer Engineering for Improved Water Management in Anion Exchange Membrane Water Electrolyzers 2024 37th ISE, Stresa / Italy, 9.-12.06.2024 J. Disch, K. Seteiz, J. Häberlein, F. Brendel, L. Bohn, S. VierrathCatalyst layer engineering and forward-bias bipolar membranes for the electrochemical reduction of CO2 to CO 2024 PSI Symposium, Villigen / Switzerland, 06.06.2024 N. Klatt, M. Hinrichs, T. HutzenlaubCentrifugal Microfluidic Automation of Proteomic Sample Preparation Techniques 2024 40th International Symposium on Microscale Separations and Bioanalysis 2024 (MSB 2024), Brno/Czech Republic, 19-22 May 2024 C. Schare, G. Titvinidze, E. Cruz Ortiz, N. Platenburg, M. Viviani, S. Vierrath, K.-D. Kreuer, C. Klose, A. MünchingerGood Stability and Low Cross-Over Hydrocarbon Based Membrane for PEM Electrolysis 2024 37th ISE, Stresa / Italy, 9.-12.06.2024 H. Liepold, S. Vierrath, C. Klose, A. MünchingerHydrocarbon-Based Catalyst Layers: A Tradeoff Analysis for PEM Fuel Cells Under Low Humidity Conditions 2024 Gordon Research Conference, Bryant University, Smithfiled, Rhode Island / USA, 29.07. – 02.08.2024 E. Cruz Ortiz, M. Viviani, N. van Treel, S. Vierrath, M. BühlerHydrogen Crossover Measurements of Proton Exchange Membranes for Water Electrolysis with in-operando Conditions 2024 37th ISE, Stresa / Italy, 9.-12.06.2024 M. Neugebauer, S. Calabrese, A. Markl, L. Schumacher, T. Wolper, T-T. Truong, P. Juelg, N. Borst, T. Hutzenlaub, F. Scherer, F. von Stetten, M. LehnertIncreasing digital PCR performance in liquid biopsy using reporter emission multiplexing 2024 13th CNAPS International Symposium on Circulating Nucleic Acids in Plasma and Serum, Graz/Austria, 4-6 March 2024 F. Brendel, L. Bohn, J. Häberlein, S. Vierrath, J. DischInvestigating water management in bipolar membrane CO2-to-CO-electrolysis with high-resolution neutron imaging 2024 PSI Symposium, Villigen / Switzerland, 06.06.2024 D. Straubinger, Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. ShuInvestigation of metal jet printing for homogeneous lines with Starjet technology 2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024 H. Gmoser, T. Groß, M. Ballweg, P. Sánchez-Martín, M. Lehnert, C. Jeney, A. Lux, P. Juelg, F. v. Stetten, N. BorstIsothermal PICO Assay for One-Step Library Prep and Nanopore Readout 2024 nanodiag bw Innovative Retreat, Hohenfels, Bodensee, 30 September - 3 October 2024 H. GmoserIsothermal PICO Assay for One-Step Prep and Nanopore Readout 2024 nanodiag bw Innovative Retreat, Hohenfels, Bodensee, 30 September - 3 October 2024 J. Häberlein, K. Seteiz, P. Heizmann, J. Disch, S. VierrathLow loaded carbon supported Ag nanoparticles for CO2 electrolysis towards CO enabling high mass activities 2024 Renewable Energy: Solar Fuels, Gordon Research Conference; Ventura, California/United States, 4 - 9 Febraury 2024 J. Häberlein, K. Seteiz, P. Heizmann, J. Disch, S. VierrathLow loaded carbon supported Ag nanoparticles for CO2 electrolysis towards CO enabling high mass activities 2024 PSI Symposium, Villigen / Switzerland, 06.06.2024 J.F. Hess, J. Rüdiger, T. HutzenlaubMicrofluidic Automation of Library Preparation for Nanopore Sequencing 2024 40th International Symposium on Microscale Separations and Bioanalysis 2024 (MSB 2024), Brno/Czech Republic, 19-22 May 2024 S. Calabrese, A. Markl, M. Neugebauer, L. Schumacher, N. Borst, F. Scherer, F. von Stetten, M. LehnertReporter emission multiplexing (REM) Increases detection capacities of digital PCR devices leading to sensitive, precise and specific liquid biopsy assays 2024 EUDIP 2024 - European Digital PCR Symposium 2024, Gent/Belgium, 6-8 February 2024 L. BohnSensing in Electrochemical CO₂ Reduction: Integrated reference electrodes for zero-gap CO₂ electrolysis cells 2024 ACHEMA, Frankfurt, 13.06.2024 Z. Khan, A. Saphala, D. Straubinger, S. Kartmann, P. Koltay, R. Zengerle, O. Amft, Z. ShuTowards hybrid printing of intelligent devices: conductive traces from bulk metal for digital signals 2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024 V. Zieger, D. Frejek, S. Zimmermann, P. Koltay, R. Zengerle, S. KartmannTransfer volume modeling for feedback-free, automated single spheroid deposition using droplet-generated microfluidic flow 2024 MFHS 2024 - The 5th Conference on Microfluidic Handling Systems, Munich, 21-23 February 2024 L. Bohn, J. Häberlein, F. Brendel, J. Disch, S. VierrathWater transport in CO2 electrolysis to CO during pulsed operation investigated by high-resolution neutron Imaging 2024 Renewable Energy: Solar Fuels, Gordon Research Conference; Ventura, California/United States, 4 - 9 Febraury 2024 L. Bohn, J. Häberlein, F. Brendel, S. Vierrath, J. DischWater transport in CO2 electrolysis to CO during pulsed operation investigated by high-resolution neutron imaging 2024 PSI Symposium, Villigen / Switzerland, 06.06.2024 back to the year overview V. Zieger, D. Frejek, S. Zimmermann, P. Koltay, R. Zengerle, S. KartmannA novel platform for automated and efficient handling of scaffold-free 3D cell-culture models enables well-controlled large-scale 3D in vitro drug screening 2023 SLAS 2023 Conference and Exhibition, San Diego, CA, USA, 25.02. - 01.03.2023 L. Metzler, S. Koch, M. Klingenhof, L. Hagner, M. Elshamy, L. Bohn, P. Strasser, S. VierrathAdvances in AEM water electrolysis – Towards scalable production of iridium-free cells with high voltage efficiency 2023 EMEA 2023, Workshop on Ion Exchange Mambranes for Energy Applications, Bad Zwischenahn, 20.-22.06.2023 B. Breiner, D. Kainz, S. Wagner, M. Gavage, S. Sahakalkan, R. Marega, F. von Stetten, A. KlebesAutomated allergen sample preparation and detection
via centrifugal microfluidic lateral flow assay 2023 Eurosensors 2023, Lecce, Italy, 10. - 13.09.2023 V. Zieger, E. Wöhr, S. Zimmermann, D. Frejek, P . Koltay, R. Zengerle, S. KartmannAutomated large scale spheroid generation via hanging drop and efficient transfer into physiological mimicking microenvironment 2023 Transducers, Kyoto/Japan, May 25-29, 2023 Z. Shu, S. Hennig, P. Koltay, S. Kartmann, F. von Stetten, R. ZengerleAutomated sample preparation platform for protein
diagnostics based on open microfluidics electrophoresis 2023 Black Forest Nanopore Meeting, Freiburg, 06.-09.11.2023 J. Disch, S. Ingenhoven, S. VierrathBipolar membranes with porous anion exchange layers for
the electrochemical reduction of CO2 to CO 2023 Carbon Capture, Utilization and Storage Gordon Research Conference, Les Diablerets, VD, Switzerland, 28.05. - 02.06.2023 K. Seteiz, J. Häberlein, P. Heizmann, J. Disch, S. VierrathCarbon black supported Ag nanoparticles for CO2 to CO
electrolysis enabling high mass activities 2023 EFCF 2023, Low Temperature Fuel Cells, Electrolysers & H2 Processing Forum, Lucerne/Switzerland, July 4-7, 2023 Y.-K. Lai, J. F. Hess, N. PaustCentrifugal gravity enables void-free priming of dead-end nanoliter cavities 2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023 T.-T. Truong, K. Mikloska, N. Paust, T. Hutzenlaub, L. Kubetzko, S. Derer, N. von Bubnoff, P. JuelgComparison of DNA reference material for pre analytics : Nucleosomal plasma spike ins reveal true recovery efficiencies of circulating cell free DNA extractions 2023 ISMRC 2023 - 13th International Symposium on Minimal Residual Cancer, Hamburg, 02.-04.05.2023 N. van Treel, R. Qelibari, E. Cruz Ortiz, G. Titvinidze, C. Klose, A. Münchinger, S. VierrathDirect coating on PEEK reinforced sulfonated polyphenylensulfone membrane 2023 ECS Meeting, Gothenburg / Sweden, 8.-12.10.2023 Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. ShuDirect conductive metal printing for one step fabrication of hybrid flexible electronics 2023 inno LAE 2023, Cambridge, UK, 21. – 23. Feb. 2023 E. Cruz Ortiz, M. Breitwieser, S. Vierrath, M. BühlerEffect of compression on the membrane electrode assembly of polymer electrolyte electrolyzers 2023 EFCF 2023, Low Temperature Fuel Cells, Electrolysers & H2 Processing Forum, Lucerne/Switzerland, July 4-7, 2023 S. Koch, J. Disch, L. Bohn, L. Metzler, S. VierrathElectrode engineering for anion-exchange membrane electrolyzers 2023 SpinCat Workshop: "Interfacial Electrochemistry and Electrolysis”, Eindhoven / The Netherlands, 13.- 14.11.2023 S. Murad, M. Heyer, F. Lickert, J. Menges, S. Calabrese, T. Hutzenlaub, N. Paust, P. JuelgFast and bubble-free filling of nano-imprinted high-density picoliter well arrays for digital assays enabled by centrifugal microfluidics 2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023 E. Mahmodi Arjmand, F. Schlenker, G. Grether, T. Tu Troung, T. Hutzenlaub, R. Zengerle, N. Paust, J. Lüddecke, P. JuelgGleichzeitige Extraktion von extrazellulären Vesikeln und zellfreier DNA aus einer einzigen Blutprobe durch zentrifugale Mikrofluidik 2023 Mikrosystemtechnik Kongress 2023, Dresden, 23.-25.10.2023 Z. ShuHybrid 3D printing of conductive metal and polymer for smart 3D electronics and sensors 2023 IVAM Hightech Summit 2023, Bochum, 03.-04.05.2023 Z. Khan, D. Gururajan, D. Straubinger, P. Koltay, S. Kartmann, R. Zengerle, Z. ShuHybrid 3D-printing of molten metal microdroplets and polymers for prototyping of printed circuit boards with integrated electrical energy storage systems 2023 Transducers, Kyoto/Japan, May 25-29, 2023 E. Cruz Ortiz, M. Viviani, N. van Treel, S. Vierrath, M. BühlerHydrogen Crossover Measurements of Proton Exchange Membranes for Water Electrolysis with in-operando Conditions 2023 ICE 2023, Sun City Resort, South Africa, 27.08. - 01.09.2023 H. Liepold, H. Nguyen, A. Muenchinger, S. VierrathInfluence of ionomer chemistry on gas permeability in hydrocarbon-based proton-exchange membrane fuel cells 2023 EFCF 2023, Low Temperature Fuel Cells, Electrolysers & H2 Processing Forum, Lucerne/Switzerland, July 4-7, 2023 H. Liepold, H.Nguyen, A. Muenchinger, S. VierrathInfluence of ionomer chemistry on gas permeability in hydrocarbon-based proton-exchange membrane fuel cells 2023 ECS Meeting, Gothenburg / Sweden, 8.-12.10.2023 B. Johannsen, D. Baumgartner, M. Karpíšek, D. Stejskal, N. Paust, R. Zengerle, K. MitsakakisIntegration of a bead-based immunoassay on a commercial PCR-performing POC device 2023 Eurosensors 2023, Lecce, Italy, 10. - 13.09.2023 , volume : 97, page : 166 H. Gmoser, T. Groß, M. Ballweg, A. Lux, C. Jeney, M. Lehnert, F. v. Stetten, N. BorstIsothermal Protein Interaction Coupling (PICO) Assay towards One-Step Library Prep and Nanopore Read-out 2023 Black Forest Nanopore Meeting, Freiburg, 06.-09.11.2023 N. BorstNeue Technologien für die molekulare Diagnostik zuhause 2023 HomeDiagnostix Congress, Konstanz, July 5-7, 2023 F. Pescher, M. von Holst, P. Heizmann, S. Vierrath, M. BreitwieserNovel Catalysts for Proton Exchange Membrane Fuel Cells via Fluidized Bed Atomic Layer Deposition 2023 EFCF 2023, Low Temperature Fuel Cells, Electrolysers & H2 Processing Forum, Lucerne/Switzerland, July 4-7, 2023 F. Pescher, M. von Holst, A. Salihi, J. Stiegeler, P. Heizmann, S. Vierrath, M. BreitwieserPlatinum Catalysts for Proton Exchange Membrane
Fuel Cells via Fluidized Bed Atomic Layer Deposition 2023 ECS Meeting, Gothenburg / Sweden, 8.-12.10.2023 C. Engelmann, C. Kleber, Y. Kaku, T.-T. Truong, N. Klatt, P. Jülg, T. Ensslen, P. Jain, J. Schwaiger, S. Kartmann, T. Hutzenlaub, A. SchreiberProtein Sample Preparation for Nanopore Technology 2023 Black Forest Nanopore Meeting, Freiburg, 06.-09.11.2023 T. Tu-Truong, Y. Kaku, S. ElGenk, M. Bösenberg, H. Sültmann, T. Gemoll, N. von Bubnoff, E. Dazert, L. Kubetzko, S. Derer, M. Oberländer, A. Katalinic, R. Deck, C. Sina, H. Busch, S. Kartmann, J. Lüddecke, T. Hutzenlaub, N. Paust, P. JuelgRobotic centrifugal microfluidics: a novel automation platform for large sample volume applications demonstrated by cell-free DNA isolation 2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023 V. Zieger, D. Frejek, S. Zimmermann, P. Koltay, R. Zengerle, S. KartmannSelective high-throughput deposition of single spheroids towards automated 3D in vitro cell culture 2023 3D Cell Culture 2023, Freiburg, 17. - 19.04.2023 L. Bohn, J. Disch, S. VierrathSeparating loss mechanisms in CO2 electolyzers by utilizing
reference electrodes 2023 EFCF 2023, Low Temperature Fuel Cells, Electrolysers & H2 Processing Forum, Lucerne/Switzerland, July 4-7, 2023 Z. ShuStarJet Technology - Direct molten metal printing for printed, flexible, 3D electronic applications 2023 TechBlick, virtuell, 29.-30.03.2023 J. Schlanderer, J. Lüddecke, A. Golubov, W. Grasse, T. A. Kohl, C. Metzger-Boddien, S. Niemann, C. Pilloni, S. Plesnik, B. Raya, B. Shresta, R. Zengerle, M. Beutler, H. Hoffmann, N. PaustTwo-Stage Tuberculosis Diagnostics: Combining Centrifugal Microfluidics at the Point-of-Care with subsequent Antibiotic Resistance Profiling by Targeted NGS 2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023 J. Schlanderer, M. Beutler, W. Grasse, T. A. Kohl, J. Lüddecke, S. Niemann, H. Hoffmann, N. PaustTwo-stage tuberculosis diagnostics: centrifugal microfluidics at the point of care with subsequent antibiotic resistance profiling by tNGS 2023 Eurosensors 2023, Lecce, Italy, 10. - 13.09.2023 S. Koch, J. Disch, S. Kilian, L. Metzler, S. VierrathWater Transport and Salt Precipitation in Anion-Exchange Membrane Electrolyzers 2023 ECS Meeting, Gothenburg / Sweden, 8.-12.10.2023 back to the year overview Z. Khan, R. Zengerle, P. Koltay, S. Kartmann, Z. Shu3D printed single-layer functional PCB via digital hybrid printing of polymer and molten metal 2022 5th International Conference on 3D Printing & Bioprinting, ΑΙ, Digital and Additive Manufacturing (I3D22) L. Riek, F. Koch, D. Frejek, L. Zausch, R. Zengerle, P. Koltay, S. Kartmann, S. ZimmermannA Bioprinting Fidelity Imager (BioFI) for a standardized characterization of bioprinting processes 2022 SLAS Europe 2022 Conference and Exhibition, Dublin, Ireland, May 26, 2022 K. Seteiz, J. Disch, S. VierrathCl doped Ag as highly porous nanoparticles for CO2 electrolysis to CO 2022 Gordons Solar Fuels, Lucca, Italy, May 8-13, 2022 C. Schwarz, F. Lombeck, H. Nguyen, F. Khan, D. Sultanova, K. Yildirim, M. BreitwieserDevelopment of roll-to-roll feasible, direct coating technique for membrane electrode assemblies 2022 Fuel Cells, Gordon Research Conference, Smithfield, RI, USA, July 24 - 29, 2022 Z. Khan, P. Koltay, R. Zengerle, S. Kartmann, Z. ShuDirect printing of molten solder via StarJet technology in Flexible Hybrid Electronics 2022 Flex Conference & Expo, San Francisco, USA, July 11-14, 2022 E. Cruz Ortiz, M. Breitwieser, S. Vierrath, M. BühlerEffect of compression on the membrane electrode assembly of polymer electrolyte electrolyzers 2022 ICE 2021, 3rd International Conference on Electrolysis 2021, Golden, Colorado USA, June 12-17, 2022 C. Schare, A. Münchinger, R. Qelibari, L. Metzler, G. Titvinidze, S. Vierrath, C. KloseEnabling the large scale production of fluorine free electrode assemblies for proton exchange membrane water electrolysis 2022 ICE 2021, 3rd International Conference on Electrolysis 2021, Golden, Colorado USA, June 12-17, 2022 J. Disch, L. Bohn, S. Koch, M. Schulz, Y. Han, M. Breitwieser, S. VierrathHigh-resolution neutron imaging of carbonate precipitation and water transport in CO2 electrolysis to CO 2022 Swiss Electrochemistry Symposium, Aarau, Switzerland, May 11, 2022 J. Disch, L. Bohn, S. Koch, M. Schulz, Y. Han, M. Breitwieser, S. VierrathHigh-resolution neutron imaging of carbonate precipitation and water transport in CO2 electrolysis to CO 2022 Gordons Solar Fuels, Lucca, Italy, May 8-13, 2022 N. van Treel, E. Cruz Ortiz, S. Vierrath, M. BühlerInfluence of the gas diffusion layer on the performance of a PEM water electrolyzer 2022 ICE 2021, 3rd International Conference on Electrolysis 2021, Golden, Colorado USA, June 12-17, 2022 D. KainzMicrothermoforming - enhancing Blister technology 2022 12th European Thermoforming Conference 2022, Vienna, Austria, 31st March - 1st April 2022 M. Trotter, A. Schreiber, D. Kleinknecht, N. Borst, M. Kuderer, K. Gläser, F. von StettenMobile elektrochemische Plattform zur molekularen Diagnostik in der häuslichen Pflege 2022 5. Müchner Poit-of-Care Testing Symposium, Munich, September,27-29, 2022 F. von StettenNovel German innovation network “nanodiag BW” - nanopore diagnostics of epigenetic markers” 2022 SMPS3 (Single-molecule protein sequencing), Delft, The Netherlands, October, 27 - November, 3, 2022 H. Nguyen, D. Sultanova, F. Lombeck, C. Schwarz, P. A. Heizmann, C. Klose, S. Vierrath, M. BreitwieserPEM fuel cells based on novel hydrocarbon ionomers: Approaching state-of-the-art performance 2022 Fuel Cells, Gordon Research Conference, Smithfield, RI, USA, July 24 - 29, 2022 J. Stiegeler, C. Schwarz, T. Mittermeier, T. Lehre, L. Tsikonis, S. VierrathPlatinum catalyst stressor studies toward realistic accelerated durability tests for heavy-duty polymer electrolyte fuel cells 2022 Fuel Cells, Gordon Research Conference, Smithfield, RI, USA, July 24 - 29, 2022 M. von Holst, L. Pavko, J. Stiegeler, P. A. Heizmann, A. Salihi, M. Gatalo, N. Hodnik, C. Klose, S. Vierrath, M. BreitwieserReduced graphene oxide as durable carbon support for PtCo catalyst in proton exchange membrane fuel cells 2022 Fuel Cells, Gordon Research Conference, Smithfield, RI, USA, July 24 - 29, 2022 V. Zieger, D. Frejek, G. Miotto, L. Riek, S. Zimmermann, P. Koltay, R. Zengerle, S. KartmannSelective and automated high-throughput deposition of spheroids for scalable 3D-bioprinting 2022 Biofabrication 2022, Pisa, Italy, September, 25-28, 2022 V. Zieger, D. Frejek, L. Riek, R. Zengerle, S. KartmannSelective high-throughput deposition of microtumors for in vitro studies on 3D tumor models 2022 SLAS Europe 2022 Conference and Exhibition, Dublin, Ireland, May 26, 2022 T. Tu Truong, F. Schlenker, L. Karkossa, E. M. Arjmand, G. Grether, J. Lüddecke, U. A. Walker, S. Giaglis, N. Paust, T. Hutzenlaub, P. JuelgTowards standardization of pre-analytics: Highly efficient platelet-poor-plasma generation for ccfmtDNA analysis on a centrifugal microfluidic platform 2022 EACR Liquid Biopsy, Bergamo, Italy, May 24-26, 2022 F. Koch, L. Riek, D. Frejek, L. Zausch, S. Zimmermann, S. Kartmann, R. Zengerle, A. Osorio-Madrazo, P. KoltayTowards standardized characterization of droplet-based bioprinting processes 2022 Biofabrication 2022, Pisa, Italy, September, 25-28, 2022 T. Lange, T. Groß, Á. Jeney, J. Scherzinger, E. S. C. Niemöller, S. Zimmermann, P. Koltay, F. von Stetten, R. Zengerle, C. JeneyValidation of scRNA-seq fold changes by single-cell reverse transcription digital PCR 2022 Single-Cell Genomics, Gordon Research Conference, Les Diablerets, VD, Switzerland, May 1- 6, 2022 S. Koch, S. K. Kilian, J. L. Disch, L. Metzler, P. A. Heizmann, Y. Han, M. Schulz, M. Breitwieser, S. VierrathWater management in anion-exchange membrane water electrolyzers under dry cathode operation 2022 GPR 2022, Golden, Colorado USA, June 12-17, 2022 S. Hennig, Z. Shu, L. Gutzweiler, P. Koltay, F. von Stetten, R. Zengerle, S. M. Früh“Paper-based open microfluidics platform for automatic protein analysis 2022 SLAS Europe 2022 Conference and Exhibition, Dublin, Ireland, May 26, 2022 back to the year overview H. Nguyen, F. Lombeck, C. Schwarz, P. A. Heizmann, M. Adamski, H-F. Lee, B. Britton, S. Holdcroft, S. Vierrath, M. BreitwieserA fluorine-free hydrocarbon-based proton exchange membrane fuel cell with state-of-the-art performance 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 J.-N. Klatt, T.-L. Dinh, O. Schilling, R. Zengerle, F. Schmidt, T. Hutzenlaub, N. PaustAutomation of Solid Phase Extraction for Peptide Desalting by Centrifugal Microfluidics 2021 37th International Symposium on Microscale Separations and Bioanalysis 2021, Boston/USA (online), 12.-15.07.2021 J.-N. Klatt, T.J. Dinh, N. Paust, R. Zengerle, F. Schmidt, O.Schilling, T. HutzenlaubAutomation of peptide desalting by centrifugal microfluidics 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online B. Johannsen, D. Baumgartner, L. Karkossa, L. Müller, N. Paust, M. Karpíšek, N. Bostanci, R. Zengerle, K. MitsakakisDetection of systemic and oral inflammation biomarkers through biochemical and microfluidic integration 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online D. Kainz, B. Breiner, R. Zengerle, N. Paust, T. Hutzenlaub, S. M. FrühDetermining binding kinetics of a PCT lateral flow assay during runtime 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online P. Juelg, E. Kipf, M. Specht, J. Menges, M. Fillies, C. Eckert, N. Paust, R. Zengerle, M. Lehnert, T. HutzenlaubDie MRD Disk: Automatisiertes Monitoring Minimaler Resterkrankung durch hochsensitive, zentrifugal-mikrofluidische Multiplex-qPCR / The MRD disk: automated minimal residual disease monitoring by highly sensitive centrifugal microfluidic multiplex qPCR 2021 MST J. Weygant, F. Koch, K. Troendle, G. Finkenzeller, R. Zengerle, S. Kartmann, S. Zimmermann, P. KoltayDrop-on-Demand Bioprinting Approach For Precise
Alignment and Interaction Studies of Different Cell Types 2021 International Conference on Biofabrication, Australia, 27. – 29.09.2021 (online) K. Tröndle, A. Itani, F. Koch, R. Zengerle, P. Koltay, S. ZimmermannDrop-on-demand bioprinting solutions for the fabrication of 3D cell culture systems 2021 DECHEMA 3D Cell Culture Freiburg (online), 05.-07.05.2021 C. Schwarz, S. Vierrath, M. BreitwieserElucidating the impact of Pt-ink ageing on fuel cell performance in laboratory scale CCM production 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 L. Niebling, S. Burger, N. Paust, A. R. HomannFast and on-site animal species identification in processed meat 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, S. Vierrath,Fluorine-free membrane electrode assemblies for water electrolysis based on sulfonated polyphenylensulfone 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 F. Schlenker, L. Karkossa, N. Paust, R. Zengerle, S. Giaglis, U. A. Walker, T. Hutzenlaub, P. JuelgGeneration of platelet poor plasma for circulating cell-free mitochondrial DNA analysis on a centrifugal microfluidic platform 2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021 M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. R. Homann, F. von Stetten, R. Zengerle, N.PaustHigh dynamic range digital assay enabled by dual volume centrifugal step emulsification 2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021 E. Ortiz, F. Lombeck, M. Kroschel, J. Hübner, L. Bohn, M. von Holst, M. Breitwieser, P. Strasser, S. VierrathHighly efficient low-loaded Ir-anodes proton exchange membrane water electrolysis: concepts to reduce in-plane resistance 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 Z. Khan, Z. Shu, R. Zengerle, P. KoltayHybrid 3D printing of polymer and solder to create functional 3D electronics 2021 EPoSS Annual Forum 2021, Freiburg, 04.-07.10.2021 F. Koch, K. Tröndle, G. Finkenzeller, P. Rukavina, R. Zengerle, P. Koltay, S. ZimmermannHybrider 3D-Biodruck zur künstlichen Herstellung von Knochen / Using hybrid processes for 3D-bioprinting of artificial bone tissue 2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021 S. Koch, S. K. Kilian, P. A. Heizmann, M. Breitwieser, S. VierrathImproving anion-exchange-membrane water electrolyzers by adjusting the ionomer content in the catalyst layers 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 M. Trotter, D. Juric, Z. Bagherian, N. Borst, K. Gläser, F. von Stetten, A. ZimmermannIntegration of nanoporous gold electrodes in microfluidic chambers by inkjet-printing for biosensing applications 2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021 J. Schlanderer, J. Lüddecke, R. Zengerle, N. PaustLarge sample volume management on centrifugal microfluidic cartridges 2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021 P. A. Heizmann, M. von Holst, H. Nguyen, F. Lombeck, C. Schwarz, C. Klose, M. Breitwieser, S. VierrathLinking morphological properties of Pt/C catalysts to electrochemical performances for improved catalysis in fuel cells 2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021 D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. MitsakakisMicrofluidic-based molecular analysis of plant psts for insecticide resistance management (Superpests-Disk) 2021 A. Brunauer, A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. FrühMultianalyte-Assays: Simultaneous detection of protein and nucleic acid biomarkers 2021 European Biosensor Symposium (EBS), online, 09.-12.03.2021 A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. FrühMultianalyte-Assays: Simultaneous detection of protein and nucleic acid biomarkers 2021 European Biosensor Symposium (EBS), online, 09.-12.03.2021 Y.-T. Kao, S. Calabrese, N. Borst, M. Lehnert, Y.-K. Lai, F. Schlenker, R. Zengerle, P. Garstecki, F. von StettenOne-step amplification-free bacteria detection by optimizes LNA/DNA molecular beacons in droplets 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online L. Becherer, J.F. Hess, S. Frischmann, M. Bakheit, H. Nitschko, S. Stinco, F. Zitz, H. Hofer, G. Porro, F. Hausladen, K. Stock, D. Drossart, H. Wurm, H. Kuhn, D. Huber, T. Hutzenlaub, N. Paust, M. Keller, O. Strohmeier, S. Wadle, N. Borst, R. Zengerle, F. von StettenPoint-of-Care System for HTLV-1 Proviral Load Quantification by Digital Mediator Displacement LAMP 2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021 P. A. Heizmann, C. Klose, M. Breitwieser, S. VierrathQuantitative STEM tomography for proton exchange membrane fuel cell apllications 2021 Symposium Nano-BW, Bad Herrenalb, online, 07.10.2021 A. Brunauer, R. D. Verboket, D. M. Kainz, F. von Stetten, S. M. FrühRapid nucleic acid lateral flow immunoassay for the detection of Pseudomonas aeruginosa 2021 Biosensors 2021, Haeundae-gu, South Korea, (online), 26. - 29.07.2021 K. Seteiz, B. Shanahan, P. A. Heizmann, S. Koch, J. Büttner, S. Ouardi, S. Vierrath, A. Fischer, M. BreitwieserRapid wet-chemical oxidative activation of graphite felt electrodes for vanadium redox flow batteries 2021 2nd Electrochemical Cell Concepts Colloquium (Virtual E3C), Oberhausen, Germany (Online), 6.5.2021 A. Klebes, A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. FrühSimultaneous detection of protein and nucleic acid biomarkers via paper-based multianalyte sensor 2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. MitsakakisSuperPests LabDisk: a microfluidic-based molecular diagnostic platform for detection of biotypes, resistance mutations and plant pathogens P3.021 2021 Biosensors, Haeundae-gu, South Korea (online), 26. – 29.07.2021 S. Vierrath, E. Cruz Ortiz, F. Hegge, T. Böhm, F. Lombeck, M. BreitwieserTackling durability and efficiency in polymer membrane fuel cells and electrolysis 2021 MRS Seattle/Washington, USA (online), 10. – 14.04.2021 P. A. Heizmann, M. von Holst, F. Lombeck, H. Nguyen, C. Klose, M. Breitwieser, S. VierrathUnderstanding the platinum carbon-support interaction for improved catalysis in hydrogen fuel cells 2021 9th NRW Nano Conference: Innovations in Materials and Applications, Münster, Germany (Online), 21.-23.04.2021 T. Härpfer, L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von StettenUniversal multiplex mediator displacement LAMP Nr. P3.062 analytical and clinical validation on the example of HIV, Haemophilus ducreyi and Treponema pallidum 2021 Biosensors, , Haeundae-gu, South Korea (online) , 26. – 29.07.2021 E. Mahmodi Arjmand, G. Grether, R. Zengerle, N. Paust, J. LüddeckeWaste liquid assisted flow-switching on a centrifugal microfluidic platform 2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021 back to the year overview A. Brunauer, B. Breiner, S. Hennig, D. Kainz, R. Verboket, B. Johannsen, D. Baumgartner, K. Mitsakakis, L. Gutzweiler, Z. Shu, P. Koltay, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, S. M. FrühActuation principles for bioanalytical platforms to combat infectious diseases 2020 Virtual EMBL Conference: Microfluidics: Designing the Next Wave of Biological Inquiry 2020, 13.-15.07.2020 J. F. Hess, M. Kotrová, S. Calabrese, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. PaustAutomated library preparation for next generation sequencing of immunoglobulin gene rearrangements by centrifugal microfluidics 2020 MicroTAS 2020, 04.-09.10.2020, virtual F. Schlenker, E. Kipf, N. Borst, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, P. JuelgCentrifugal microfluidic 4 Plex digital droplet PCR for quantification of circulating tumor DNA 2020 MicroTAS 2020, 04.-09.10.2020, virtual F. Lombeck, F. Hegge, M. von Holst, C. Klose, S. Vierrath, M. BreitwieserCeramic Nanofibers: A versatile material class to improve Electrochemical Energy Applications 2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020 K. Tröndle, A. Itani, F. Koch, R. Zengerle, S. Zimmermann, P. KoltayFabrication and fluidic integration of self-assembled cellular microtubules for nephron-on-chip applications 2020 MicroTAS 2020, 04.-09.10.2020, virtual H. Nguyen, P. A. Heizmann, F. Lombeck, A. Belletti, B. Britton, S. Vierrath, M. BreitwieserImproving the Performance of All-Hydrocarbon PEM Fuel Cells Based on Pemion™ Ionomer 2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020 F. Schlenker, E. Kipf, M. Deuter, I. Hoeffkes, N. Borst, T. Hutzenlaub, R. Zengerle, F. von Stetten, N. von Bubnoff, P. JuelgLow optimization effort for highly sensitive assays for point mutation quantification in CTDNA: the Mediator Probe digital PCR 2020 Liquid Biopsy Symposium, 30.10.2020, virtuell P. Koch, O. Barth, M. Meyer, R. Streller, R. Zengerle, M. Rombach, M. JehleMicrothermoforming: Enhancing blister technology to introduce microstructures in functional packaging 2020 12. European Thermoforming Conference, Geneva, Switzerland, 18.-20.03.2020 M. Breitwieser, S. VierrathOne for all or one for each application? Recent advances in membrane & ionomer development for electrochemical energy converters 2020 E3C Electrochemical Cell Concepts Colloquium Fraunhofer UMSICHT, 14.05.2020 E. Cruz Ortiz, F. Hegge, M. Breitwieser, S. VierrathPerformance Improvement of PEM Water Electrolyzer Anodes via a Bi-Functional Binder Polymer Blends for Ionic and Electrical Conduction 2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020 M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, K. MitsakakisRespiDisk: A Point-of-Care platform for fully automated detection of respiratory tract infection pathogens in clinical samples 2020 MicroTAS 2020, 04.-09.10.2020, virtual S. Koch, C. Klose, B. Britton, M. Breitwieser, S. VierrathTowards stable catalyst layers for water electrolysis based on anion-exchange membranes 2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020 B. Johannsenid Diagnosis of Respiratory Tract Infections Using a Point-of-Care Platform Incorporating a Clinical Decision Support Algorithm 2020 pHealth2020, 14. – 16. 09. 2020 back to the year overview S. Kartmann, D. Kopp, M. Masoumi, R. Zengerle, H. Zappe, P. KoltayThermischer Einweg-Strömungssensor auf Basis einer flexiblen Polyimid-Folie 2019 MicroTEC Südwest Clusterkonferenz, Freiburg, 20.-21.03.2019 » show abstract « hide abstract Abstract --- M. Lehnert, E. Kipf, F. Schlenker, R. Zengerle, N. Borst, F. von StettenMultiplex Mediator Probe Real-Time PCR - Optimization and Guideline Development through Systematic Characterisation of Label Free Mediator Probes and Fluorogenic Universal Reporters
2019 9th Gene Quantification Event qPCR dPCR & NGS 2019, 18 - 22 March 2019, in Freising-Weihenstephan, Germany » show abstract « hide abstract Abstract Mediator Probe PCR is a powerful and robust real-time PCR technology for multiplex DNA detection and quantification. It uses label free mediator probes, for molecular detection of nucleic acids during DNA amplification, in combination with fluorogenic universal reporters for signal generation. During PCR, target sequence specific mediator probes are cleaved by the polymerase and a generic sequence, the mediator, is set free. In the second step the mediator binds to the universal reporter, where it is extended by the polymerase. This generates a strong fluorescence signal increase. Due to the separation of DNA detection and signal generation many advantages arise. Mediator probes are not limited in their design by properties of the target sequence and a standard set of highly optimised fluorogenic universal reporters can be used for multiplex Mediator Probe PCR, right from the start.1
In the last years Mediator Probe PCR evolved from an innovative new method to an optimised and robust multiplexing technology. This was achieved by systematic characterisation of its molecular processes, which again was advantaged by the separation of DNA detection and signal generation. A DoE approach was used for the optimisation of Mediator Probes, focusing on their binding strengths.2 In parallel, a set of universal reporters with improved signal-to-noise ratios was established by successive testing over 40 molecular structures with different fluorophore-quencher labels and configurations.1
As a result, distinct guidelines exist, which enable fast adaption of new DNA targets and facilitate multiplex Mediator Probe PCR design. The capability of the technology was shown by highly sensitive, precise and specific multiplex Mediator Probe real-time PCRs in different areas of molecular diagnostics. These fields include monitoring of oncological disease, detection of pathogens or analysis of food samples.1,3 B. Shanahan, T. Böhm, B. Britton, S. Holdcroft, S. Vierrath, S. Thiele, M. Breitwieser30 μm thin hexamethyl-p-terphenyl poly(benzimidazolium) anion
exchange membrane for vanadium redox flow batteries 2019 The International Flow Battery Forum, Lyon/France, 09 - 11 July 2019 S. Nessler, S. Kartmann, L. Mutter, C. Grandauer, M. Marx, R. Zengerle, Y. ManoliA Capacitive Readout Circuit for a Disposable Low-Cost Pressure and Flow Sensor with
200 Pa or 170 nl/s Resolution
2019 IEEE Sensors, 27. – 30. October 2019, Montreal / Canada B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S. M. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. MitsakakisAutomated pre-analytic processing of whole saliva on a centrifugal microfluidic platform for protein biomarker analysis 2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland F. Schlenker, E. Kipf, S. Jenne, N. Borst, J. Lüddecke, K. Dormanns, T. Hutzenlaub, J. Steinert, N. Paust, R. Zengerle, F. von Stetten, P. JuelgDoubling the order of color-multiplexing by photobleaching in Mediator Probe droplet digital PCR 2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17. 05. 2019 C. Siber, L. Lautscham, J. Schoendube, P. Reichert, F. Stumpf, S. Zimmermann, R. Zengerle, P. KoltayEffective acoustic field generation in diposable dispensing cartridges for acustophoretic particle focusing 2019 Transducers 2019, Berlin, 23.06. - 27.06.2019 J. Weisemann, G. B. Stevens, T. van Oordt, N. Krez, K. Dormanns, M. Karle, F. von Stetten, A. RummelFast automatic detection of Botulinum neurotoxin by the BoNT LabDisk assay: results of a trans-european performance study 2019 Toxins 2019, Copenhagen/Denmark, 16. - 19.01.2019 » show abstract « hide abstract Abstract Botulinum Neurotoxins (BoNT) are the most toxic naturally occurring substances for humans. After potential intoxication and occurrence of botulism symptoms, urgent detection of causative BoNT is highly desirable for successful medical treatment. The mouse bioassay (MBA) as gold standard requires a large number of mice, takes several days and is not suitable for point-of-care.
Here, we developed an automatic in vitro assay to detect BoNT in complex biological matrices. The assay detects specific cleavage of SNARE proteins by BoNTs by fluorescent read out in a centrifugal microfluidic cartridge, termed BoNT LabDisk (BLD). The generic LabDisk comprises two different peptides able to distinguish between BoNT/ACE and BDF, respectively. The BLD prototype system was tested in a trans-European performance study by five naïve laboratories with expertise in BoNT detection to demonstrate practical applicability and performance of the BLD system. Eight blinded samples containing three complex biological matrices (human serum, bean juice, carrot juice) or buffer spiked with 10-1000 pM of BoNT/A and D were provided. Stability of samples was confirmed by mouse hemidiaphragm assay prior to shipment.
The laboratories detected absence or presence of BoNT/A in 34 of the 40 samples correctly (85% accuracy). In three of ten bean juice or serum samples problems occurred due to high viscosity which requires improvement of sample preparation. In another three samples, signals close to background led to misinterpretation by experimentators. Altogether, the performance study showed that handling of the BLD assay is very easy, fast and practicable. The current detection limit is close to that of MBA.
In conclusion, the BLD system allows the detection of functionally active BoNT in short assay times with low limits of detection within different matrices, without the need of animals or animal based reagents. The next step will be the adaption of the BLD assay for a direct serotyping of BoNT/A-F. D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. PaustFlow profile through exposed porous media in centrifugal microfluidics 2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland Z. Shu, B. Gerdes, M. Fechtig, R. Zengerle, P. KoltayHighly conductive flexible and 3D metallization on flexible and textile substrates via StarJet Technology 2019 12th International Symposium on Flexible Organic Electronics (ISFOE19) 1-4 July 2019, Thessaloniki, Greece » show abstract « hide abstract Abstract Highly conductive metallizations are crucial for large area organic and printed electronics. State-of-the-art printing technologies such as inkjet printing and screen printing are still facing critical challenges regarding achieving high electrical conductivity and reducing the manufacturing costs. Moreover, additional post-processes such as thermal, photonic or laser sintering are either not compatible with the flexible substrates or expensive. On the contrary, the non-contact StarJet printing technology provides direct metallization from molten metal microdroplets and continuously Jet. It bases on a pneumatically driven printhead that features a heatable reservoir and an interchangeable nozzle chip with a star-shaped orifice geometry. Thanks to the pneumatic driven mechanism, materials with high melting temperature such as solder or aluminium alloys can be printed. Single-pass conductive features, printed via StarJet, exhibit high electrical conductance (7.5 Ω/m for 250 μm linewidth), high aspect ratio, i.e. high layer thickness (70 – 300 μm), and require no post-treatment. Examples of electrically functional, direct metallization were demonstrated on silicon solar cells and PCB boards. In this contribution, we demonstrate that the StarJet technology is also compatible with temperature sensitive flexible substrates such as polymer foils and textiles. The printed solder lines exhibit not only high electrical conductance but also high mechanical stability (i.e. adhesion) and high flexibility. The printed solder lines on polymer foils and textile can stand shear forces of up to 3000 mN and at the same time tolerate substrate bending at the radius of 5 mm. Furthermore, because the printed solder droplets fuse together, freestanding structures with different angles can also be printed via controlling process parameters. In summary, the StarJet technology shows high potential in direct metallization for large area flexible and wearable electronics and 3D electronic applications. F. Hegge, E. Cruz Ortiz, S. Thiele, S. VierrathImproving the performance of low loaded PEMWE electrodes 2019 2nd International Conference on Electrolysis (ICE), Loen / Norway, 9. – 13. 06.2019 P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Baensch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. HutzenlaubIndividual Response Monitoring Assay (IRMA) – Standardization Of Personalized Multiplex Biomarker Quantification 2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17.05. 2019 S. Burger, L. Drechsel, A. Homann, F. von Stetten, R. Zengerle, N. PaustLabSlice XL – A centrifugal microfluidic cartridge for the automated bio-chemical processing of industrial process water 2019 Transducers, Berlin, 23. - 27. 06. 2019 M. Specht, J. Schemberg, T. Förster, S. Burger, M. Rombach, N. Paust, R. Zengerle, F. von Stetten, G. Gastrock, M. KarleMicrofluidic App for centrifugal separation and purification of lymphatic cancer cells from whole blood 2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin S. Hin, N. Paust, M. Rombach, J. Lueddecke, M. Specht, R. Zengerle, K. MitsakakisMinimizing ethanol carry-over in centrifugal microfluidic nucleic acid extraction by advanced bead handling and management of diffusive mass transfer 2019 Transducers 2019 - EUROSENSORS XXXIII, 23.-27. Juni 2019 - Berlin, Germany » show abstract « hide abstract Abstract We present three concepts for centrifugal
microfluidics reducing ethanol carry-over in magnetic
bead-based nucleic acid (NA) extraction. Ethanol
carry-over is critical regarding inhibition of
downstream NA amplification. We identified two
possible carry-over pathways: Liquid co-transport
within bead-clusters and vapor diffusion. For the first
time, we integrated magnetic bead handling in
centrifugal microfluidics at continuous rotation aiming
to avoid liquid co-transport within bead-clusters.
Consequently, no significant contribution to ethanol
carry-over could be assigned anymore to liquid cotransport.
Major carry-over was attributed to diffusive
transport of ethanol vapor. Countermeasures reduced
this from 9.7 % (v/v) to 0.4 % (v/v), below the critical
level for inhibition of downstream amplification
reactions. P. Holzapfel, M. Bühler, C. Pham, S. ThieleMolybdenum sulphide based cathodes for PEM water electrolysis – catalyst synthesis and loading variation 2019 EFCD Conference 15.-18. September 2019, La Grande Motte, France M. Bühler, P. Holzapfel, M. Bierling, S. ThielePorous transport electrodes for PEM water electrolysis: improved performance via studying materials interfaces 2019 ICE Conference 9.-13. Juni 2019, Loen, Norway F. Koch, M. Wehrle, K. Tröndle, P. Koltay, G. Finkenzeller, R. Zengerle, S. ZimmermannRapid assessment of combined drop on demand and extrusion-based bioprinting with controlled shear stress and high shape fidelity 2019 Transducers 2019 - EUROSENSORS XXXIII 23. -27. Juni 2019 - Berlin, Germany » show abstract « hide abstract Abstract We present a novel combination of drop on demand
(DoD) and extrusion-based bioprinting to generate highprecision
patterns of cells inside large hydrogel volumes.
Extrusion-based bioprinting has the great advantage
of enabling a fast deposition of high viscous cell-loaded
hydrogel with reasonable precision. Compromises
between high shape fidelity and cell viability, as well as
short process times often require many iterations of
optimizing process parameters and varying compositions
of the hydrogel. To limit the multitude of parameters
during extrusion-based bioprinting, a method for rapid
process assessment was developed. This enables to define
limits for printing temperature, flow rate and nozzle size
from basic rheological measurements with regard to the
biological and mechanical requirements.
The combination of extrusion-based bioprinting with
DoD bioprinting allows for precise deposition of low
viscous cell suspension and adjustable concentrations of
crosslinking agent. Together, the technologies were used
to print a bone replacement model by using the predefined
process parameters. Adiposed-derived stem cells
(ASC) prone to osteogenic differentiation were
homogenously extruded in a cuboid structure of
10x10x5 mm. Human umbilical vein endothelial cells
(HUVEC) were printed as highly dense cell suspension
lines inside the extruded hydrogel to allow a potential
vascularization of the structure in vivo. F. Koch, M. Wehrle, K. Tröndle, P. Koltay, G. Finkenzeller, R. Zengerle, S. ZimmermannRapid assessment of extrusion based bioprinting by controlling shear stresses on cells 2019 Transducers 2019, Berlin, 23.06. - 27.06.2019 T. Boehm, M. S. Mu’min, R. Moroni, S. Thiele, S. Vierrath, M. BreitwieserResolving structure and properties in ionomer composite membranes with Confocal Raman Microscopy 2019 Workshop on Ion Exchange Membranes for Energy Applications, Bad Zwischenahn, 25. -27.06. 2019 T. Boehm, M. S. Mu’min, R. Moroni, S. Thiele, S. Vierrath, M. BreitwieserResolving structure and properties in ionomer composite membranes with Confocal Raman Microscopy 2019 FDFC 2019 - 8th International Conference on Fundamentals and Development of Fuel Cells Nantes/France, 12. – 14.02.2019 A. Brunauer, F. von Stetten, S.M. FrühSensitive detection of Pseudomonas
aeruginosa based on recombinase polymerase amplification combined with an immunological
assay
2019 Molecular Diagnostics Europe, Lissabon/Portugal, 06. - 09.05.2019 P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Bänsch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. HutzenlaubStandardization of Personalized Multiplex Biomarker Quantification: Individual Response Monitoring Assay (IRMA) 2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin B. Johannsen, L. Karkossa, D. Baumgartner, L. Müller, R. Zengerle, K. MitsakakisStorage of protein coated beads on point-of-care microfluidic cartridges for immunoassay applications 2019 MNE 2019, 23-26.09.2019, Rhodes/Greece P. Trinke, B. Bensmann, C. Klose, S. Vierrath, S. Thiele, R. Hanke-RauschenbachSystem relevant Observation of Gas Crossover – Necessity of Mitigation Strategies 2019 international Conference on Electrolysis, Leon (Norway), 09. - 13. 06.2019 S. M. Früh, D. M. Kainz, T. Hutzenlaub, R. Zengerle, N. PaustTailor-made immunological reactions in lateral flow strips enables by total flow control
2019 Wissenschaftsforum Chemie, Aachen, 15. -18.09.2019 P. KoltayTowards a generic 3D-Bioprinting Platform 2019 IS2M Annual Meeting, 3D & 4D printing in Upper Rhine Valley, Mulhouse/France, 06. - 07. 06. 2019 A. Brunauer, B. Breiner, D. Kainz, R. Verboket, F. von Stetten, R. Zengerle, N. Paust, T. Hutzenlaub, S. M. FrühTowards digital diagnostic devices - From smart membrane cartridges to highly integrated test stripes 2019 Diagnostics-4-Future, 27. – 28. 11. 2019, Konstanz M. Buehler, F. Hegge, P. Holzapfel, S. ThieleTowards direct membrane deposition (DMD) for PEM water electrolyzers – development of innovative electrodes deposited directly on porous transport substrates 2019 f-cell Stuttgart, 18.- 19. September 2018 F. von StettenUniversal microarray for voltammetric real-time detection of DNA-amplification by mediator displacement loop mediated isothermal amplification (MP LAMP) 2019 4th “NanoBio Surfaces and Interfaces in Healthcare and Science Workshop” 16.-17.5.2019, Potsdam back to the year overview B. Shanahan, B. Britton, S. Holdcroft, R. Zengerle, S. Thiele, M. Breitwieser30 μm thin, highly conductive PBI-based anion exchange membrane (AEM) for VRFB applications 2018 IFBF - The International Flow Battery Forum, Lausanne/Schweiz, 10. – 12.07.2018 C.-H. Tsai, D.- H. Kuan, S. Zimmermann, J. Schoendube, A. Gross, R. Zengerle, P. KoltayA highliy parallel microbioreactor for cell line development based on a microtiter plate with functional microfluidic lid 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan Z. Bagheryan, M. Trotter, L. Becherer, N. Borst, F. von StettenA universal approach for electrochemically DNA detection based on mediator displacement LAMP 2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. HutzenlaubAutomation of qPCR based Minimal Residual Disease Monitoring by Centrifugal Microfluidics 2018 11th Symposium on minimal residual cancer, 03. – 05.05.2018, Montpellier, Frankreich K. Tröndle, S. Kartmann, L. Gutzweiler, R. Zengerle, P. Koltay, S. ZimmermannBioprinting with spheroids: Automated large-scale production and deposition 2018 3D Cell Culture 2018, 5. - 7. Juni 2018, Freiburg J. F. Hess, S. Yazar, N. Paust, R. Zengerle, T. HutzenlaubCapillary Valve for Microfluidic Foil Chips Fabricated by Micro-Milled Metal Master Tools 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan F. Hegge, R. Moroni, E. Wright, J. Sharman, S. Thiele, S. VierrathCatalyst Support Ageing of Polymer Electrolyte Fuel Cells Investigated with Tomography 2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018 N. PaustCentrifugal Microfluidics:Unique operations enabled by artificial buoyancy 2018 Lab-on-a-Chip and Microfluidics Europe 2018, Rotterdam/Niederlande, 05. - 06.06.2018 N. Wipf, K. Mavridis, S. Hin, K. Mitsakakis, M. Specht, S. Medves, B. Carman, P. Müller, J. VontasDevelopment of multiplex TaqMan assays for the LabDisk – an automated diagnostic platform for malaria vectors
2018 7th MIM Pan African Malaria Conference - Dakar, 18.04.2018 S. Hin, B. Lopez-Jimena, M.A. Bakheit, V. Klein, S. Stack, C. Fall, A.A. Sall, K. Enan, S. Frischmann, L. Gillies, M. Weidmann, S. Goethel, V. Rusu, O. Strohmeier, N. Paust, R. Zengerle, K. MitsakakisDifferential diagnosis of fever in West- and East-Africa 2018 WHO Geneva Health Forum, 10. – 12.04.2018, Genf / Schweiz Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. KoltayDirect Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates 2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018, Dresden, 23. – 27.09.2018 Society for Imaging Science and Technology. Z. Shu, B. Gerdes, M. Fechtig, L. Riegger, R. Zengerle, P. KoltayDirect Printing of Conductive Metal Lines from Molten Solder Jets via StarJet Technology on Thin, Flexible Polymer Substrates 2018 NIP & Digital Fabrication Conference, Printing for Fabrication 2018 Society for Imaging Science and Technology, volume : 2018, issue : 1, pages : 72 - 75» show abstract « hide abstract Abstract We present the direct printing of thin (linewidth of 70 μm) conductive lines from molten solder on thin, flexible substrates. The lines are generated via the so-called StarJet technology that enables the printing of micro jets from molten metal. In this work, metal lines are printed for the first time on flexible substrates, possibly enabling applications in the field of printed electronics. The printed lines are evaluated regarding their mechanical and electrical properties. To the knowledge of the authors, this is the first time that direct printing of a functional metallization, requiring no further treatment, on a flexible polymer substrate was demonstrated. The lines exhibit a low ohmic resistance and can endure shear forces of up to 3.5 N on polyethylene terephthalate (PET) substrates. K. TröndleDrop-on-Demand Bioprinting Process for Single-Spheroid Deposition and Immobilization 2018 International Conference on Biofabrication, Würzburg, 28. – 31.10.2018 C. Klose, L. Bohn, M. Klingele, S. Thiele, R. Zengerle, M. Breitwieser, S. VierrathDynamic Quantification of Water Generation and Migration in Polymer Electrolyte Membrane Fuel Cells 2018 69th annual meeting of the International Society of Electrochemistry, Bologna (Italy), 02. - 07.09.2018. C. Klose, L. Bohn, M. Klingele, S. Thiele, R. Zengerle, M. Breitwieser, S. VierrathDynamic Quantification of Water Generation and Migration in Polymer Electrolyte Membrane Fuel Cells 2018 Gordon’s Research Conference on Fuel Cells, Smithfield (USA), 29.07. - 03.08.2018 L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von StettenFluorogenic real-time detection of
loop-mediated isothermal amplification by novel mediator displacement probes demonstrated for HIV-1 and HTLV-1
2018 International Biotech Innovation Days, 23 - 25 May 2018 / Senftenberg, Germany M. Schulz, N. Borst, M. Specht, S. Calabrese, F. von Stetten, R. Zengerle, N. PaustFrom nasal swab to digital answer: unit operations for antibiotic resistance screening on a single cell level 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan L. Becherer, M. Schulz, H. Kuhn, M. Bakheit, S. Frischmann, F. Zitz, N. Borst, R. Zengerle, F. von StettenHIV-1 and HTLV-1 multiplex detection by digital mediator displacement LAMP 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan C. Klose, L. Bohn, M. Klingele, M. Breitwieser, S. VierrathHow engineering the PEM|CL interface influences the performance of PEMFCs 2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018 C. Klose, L. Bohn, M. Klingele, M. Breitwieser, S. VierrathInfluence of the PEM|CL interface on performance and water management 2018 Gordon Research Conference, Bryant University, Douglas Pike in Smithfield, RI, US., 29.07. – 03.08.2018 P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, R. Zengerle, T. HutzenlaubLabDisk for fully automated quantification of two leukemia associated gene targets 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan M. Trotter, N. Borst, F. von StettenMediator probes for electrochemical DNA detection: Universal electrode functionalization for specific detection of different targets 2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland M. Buehler, F. Hegge, P. Holzapfel, S. ThielePorous Transport Electrodes – The Influence of Depositing Electrodes on Porous Transport Layers on the Polarization Behaviour of PEM Water Electrolyzers 2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09. 2018 » show abstract « hide abstract Abstract 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09. 2018 L. Becherer, N. Borst, R. Zengerle, F. von StettenSimultaneous detection of HIV and HTLV by mediator displacement loop-mediated isothermal amplification 2018 6th World Congress on Control and Prevention of HIV/AIDS, STDs & STIs, Zürich/Switzerland, 27. – 28.08.2018 » show abstract « hide abstract Abstract 6th World Congress on Control and Prevention of HIV/AIDS, STDs & STIs, Zürich/Switzerland, 27. – 28.08.2018 T. A. Kohl, M. Beutler, M. Merker, T. Paprotka, K. Rönsch, M. Schmitt, W. Grasse, C. Metzger-Boddien, K. Dormanns, J. Lüddecke, N. Paust, J. Schlanderer, L. Delamotte, J. Schickedanz, M. Steinwand, S. Niemann, H. HoffmannTB-SeqDisK: A microfluidics platform in combination with next generation sequencing for ultra-fast notification of Mycobacterium tuberculosis and its resistance pattern 2018 39th Annual Congress of European Society of Mycobacteriology, Dresden, 01. – 04.07.2018 S. Vierrath, M. Klingele, S. Thiele, R. Zengerle, M. BreitwieserTailoring the membrane│electrode interface: a review and perspective of novel engineering approaches 2018 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018 » show abstract « hide abstract Abstract 69th Annual Meeting of the International Society of Electrochemistry (ISE), Bologna/Italy, 02. – 07.09.2018 D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. PaustTotal flow control for lateral flow tests with centrifugal microfluidics 2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. HutzenlaubTowards Standardization of Molecular Diagnostic Workflows: Centrifugal Microfluidic Automation of qPCR for Cancer Monitoring
2018 6th International Molecular Diagnostics Europe, Lissabon / Portugal, 22. - 24. 05.2018 P. KoltayTowards a generic 3D-Bioprinting Platform 2018 International Conference on Biofabrication, Würzburg, 28. – 31.10.2018 » show abstract « hide abstract Abstract ; “”, (2018), International Conference on Biofabrication, Würzburg, 28. – 31.10.2018 M. Mu’min Solihul, T. Böhm, S. Thiele, M. BreitwieserTowards more hydrophilic proton exchange membranes: adjusting the wetting properties by electrospinning PVDF-HFP/PVP blends 2018 ELEN Electrospinning for Energy, Montpellier / Fracne, 13. - 15.06.2018 C. Siber, F. Stumpf, J. Schöndube, S. Zimmermann, P. Koltay, L. LautschamVelocity field analysis of acoustophoretic focusing in a single-cell printing system 2018 Acoustofluidics, Lille/France, 29. – 31.08.2018 back to the year overview S. Zimmermann, J. Riba, R. Zengerle, P. KoltayA single-cell printer as a versatile tool for cell line development and single-cell analysis 2017 LAPASO - Microfluidics for label-free particle sorting, Lund / Sweden, 05. - 06.09.2017 » show abstract « hide abstract Abstract Single-cell analysis emerged as a promising approach to decipher the heterogeneity of complex cell populations such
as tumors. Furthermore, the proof of monoclonality is a regulatory requirement in cell line development, where a cell
population producing a therapeutic protein in a bioreactor has to originate from a single cell. Within the advent of such
diverse applications, a number of single-cell isolation technologies have been developed and adapted for different
requirements [1]. Limitations of these technologies regarding the uniqueness and the integrity of the cells can be
overcome by a single-cell printer (scp), a laboratory device developed by the University of Freiburg and
commercialized by the spin-off company cytena. J. Madjarov, P. Kocatürk Schumacher, S. Abdu, S. KerzenmacherIntegration of a microbial fuel cell anode into membrane
bioreactors treating synthetic brewery wastewater 2017 BW-Stiftung Forschungstag 2017, Stuttgart » show abstract « hide abstract Abstract Microbial fuel cells (MFCs) are a promising new technology to
directly convert wastewater’s chemically stored energy into
electrical energy. Our work shows that a conductive
membrane filter can simultaneously be used as anode of a
MFC, so that the energy demand of the filtration unit of an
anaerobic membrane bioreactor (AnMBR) can be partly
supplied by the MFC. At the same time, COD (chemical
oxygen demand) reduction is enhanced by the degradation of
organic carbon to electricity and CO2 on the membrane. M. Buehler, S. Vierrath, C. Klose, F. Hegge, S. ThieleA Novel Fabrication Technique for Electrodes of PEM Water Electrolyzers 2017 232nd ECS MEETING Oct. 1-5, 2017 | National Harbor, MD (greater Washington, DC area) » show abstract « hide abstract Abstract In this work the improvement of material interfaces at electrodes for proton exchange membrane (PEM) water electrolyzers is addressed by a novel fabrication technique. In this approach the electrode and the membrane are directly deposited on the porous transport layers (PTLs), which serve as substrate for the electrodes. The aim is to stabilize and increase the oxygen and hydrogen evolution rate at high current densities leading to a reduction of the noble metal loading of the electrodes – and additionally to develop a cost effective novel fabrication technique applicable for the large scale industrial fabrication of electrodes for PEM water electrolyzers. The innovative manufacturing technique is described in this transaction, and current challenges regarding the coating of porous substrates in terms of parameter control, reliability and homogeneity are pointed out. S. Kartmann, F. Koch, A. Ernst, R. Zengerle, P. KoltayA single-use in-line flow sensor fore closed-loop controlled precise non-contact liquid dispensing 2017 MFHS, Twente / The Netherlands, 04. - 06.10.2017